DESCRIPTION OF THE BISBEE QUADRANGLE

By Frederick Leslie liansome.

INTRODUCTION. Fifty or sixty miles south of the river rise the San the Mexican border past Tucson, Florence, and country. The hills become relatively low, and Francisco Mountains. They are all volcanoes, and four Phoenix, and thence northwestward to Needles, near before Tombstone is reached are divided into semi­ PHYSIOGRAPHIC DIVISIONS OF ARIZONA. of them are of large dimensions. The largest, San Fran­ the California line. The Mountain Region and detached clusters by broad embayments of Quater­ cisco Mountain, nearly 13,000 feet high, might be The Territory of Arizona may be divided into classed among the largest volcanic piles of the West. the Desert Region are both included in the Basin nary alluvium, continuous with that flooring San three physiographic regions (see fig. 1). The first Around these four masses are scattered many cones, and Range system of Gilbert. Pedro or Sulphur Spring valleys. Just southeast of these, occupying the northeastern portion of the the lavas which emanated from them have sheeted over The main drainage of the Mountain and Desert of Tombstone these island-like hills connect the Territory, is included within the Colorado Plateaus, a large area. The foundation upon which they are regions is transverse to the trend of the ranges, main mass of the Mule Mountains with the south­ that wonderful province which the writings of planted is still the same platform of level Carboniferous through the Gila, Salt, and Williams rivers, into ern end of the linear Dragoon Range, and form a strata which stretches calmly and evenly from the base the Colorado River. The minor drainage is by low divide between Sulphur Spring and San Pedro Powell, Gilbert, and Dutton have made classic of the Vermilion Cliffs for more than 150 miles south­ ground in geology. This division, which within ward, patched over here and there with the lingering streams, many of them intermittent in character, valleys. the boundaries of Arizona has an area of about remnants of lower Permian strata and isolated sheets of occupying in general the valleys between the par­ Five miles southeast of Mule Pass the width of 45,000 square miles, drains northward, through basalt. South of the San Francisco Mountains the level allel ranges. the range contracts rather abruptly to about 5 Carboniferous platform extends for 20 or 30 miles, and miles, and this narrowed portion decreases in gen­ the Colorado Chiquito (Little Colorado), Rio LOCATION OF THE BISBEE QUADRANGLE. Puerco, and smaller streams, into the Grand Can­ at last ends abruptly in the Aubrey Cliffs, which face eral altitude toward the Mexican border, where southward and south westward, overlooking the sierra The Bisbee quadrangle is in Cochise County, in the range terminates in a low, broad pass through yon of the Colorado. Its southeastern limit trav­ country of central Arizona. erses the Territory in a general southeasterly the southeastern part of Arizona and within what which the international boundary line runs from direction from the Grand Wash, near the eastern It is the rolling, partly timbered surface of this has been termed the Mountain Region. It lies Sulphur Spring, Valley to the valley of the San border of Nevada, to the New Mexico line, a few great plateau, surmounted by isolated volcanic between the meridians 109° 45' and 110° 00' and Pedro. The geological structure of the southeast­ miles northeast of Clifton. This limit is not every­ mountains, which surrounds the traveler as he the parallels 31° 30' and 31° 20', the latter being ern end of the Mule Mountains continues across where clearly defined. For about 240 miles, extend- journeys across the Territory from New Mexico, locally the Mexican boundary line. The area of this pass, however, and the Morita Hills in Mexico, by way of Holbrook and Flagstaff, to Ash Fork on the quadrangle is about 170 square miles, and just south of the boundary line, are made up of in O2; from the mouth of Diamond Creek on the Colo- rado River to the Adcinity of Fort Apache, the edge the Atchison, Topeka and Santa Fe Railroad. includes the southeastern half of the Mule Moun­ rocks similar to those composing the southern end of the plateau is marked, according to Gilbert in The second physiographic division, which may tains, one of the smaller of the isolated ranges of the Mule Mountains. the Wheeler Survey reports, by the continuous line be called the Mountain Region, adjoins the Plateau characteristic of the Mountain Region of Arizona. On their northeast side the Mule Mountains pre­ of the Aubrey Cliffs, which divide the waters of Region on the southwest, and is essentially a broad The Mule Mountains, while less markedly linear sent a fairly straight front, their slopes rising with zone of short, nearly parallel ranges extending than the Dragoon, Huachuca, Chiricahua, and moderate steepness from the gently inclined detrital diagonally across the Territory from the southeast other neighboring ranges, have a general north­ plain forming the. southwestern part of Sulphur corner northwesterly to Colorado River. The west-southeast trend. They may be considered as Spring Valley. The line separating the mountains width of this zone may be taken as from 70 to 150 extending from the old mining town of Tombstone from the San Pedro Valley on the southwest is miles, but, as will be later seen, its southwestern to the Mexican border, a distance of about 30 much more sinuous and the mountain front is boundary is not susceptible of precise demarcation. miles. On the northeast they are separated by the more variable in slope and height. Gently sloping It is characterized by numerous nearly parallel, broad, flat floor of Sulphur Spring Valley from plains continuous with the floor of the main valley short ranges, separated by valleys deeply filled with the Chiricahua Range, and on the southwest by extend, bay-like, into the mountain mass. The fluviatile and lacustrine deposits. The individual the similar broad valley of .the Rio San Pedro town of Naco lies in such an embayment, which in ranges, such as the Dragoon, Chiricahua, Pinalino, from the Huachuca Range. this case not only extends into the Mule Moun­ Caliuro, Santa Catalina, Tortilla, Final, Supersti­ The town of Bisbee, with an estimated popula­ tains, as Espinal Plain, but separates this range tion, Ancha, and Mazatzal mountains, rarely tion of about 6000, is crowded into a few narrow, from the San Jose Mountains in Mexico, just exceed 50 miles in length or 8000 feet in altitude. confluent ravines near the heart of the range, 7^ southwest of Naco. Their general trend is nearly northwest and south­ miles north of the international boundary. On Within the Mule Mountains may be distinguished east, but near the Mexican border it becomes the east it is connected by the El Paso and South­ two topographic divisions, based upon geological more nearly north and south, and the mountain western Railroad with the new town of Douglas, structure and roughly separated by a northwest- zone as a whole coalesces with a belt of north-south in Sulphur Spring Valley, and with Deming and southeast . line passing through Bisbee, through ranges which extends northward through New El Paso; on the west, branches of the same road run Mule Pass, and down Tombstone Canyon. North­ Mexico and borders the Plateau Region on the to Naco, on the Mexican boundary, and to Benson, east of this line the mountains are sculptured from east. The northwesterly belt of Arizona is on the main line of the Southern Pacific Railroad. comparatively soft Mesozoic beds striking approxi­ described by Gilbert as continuous with the Basin At Douglas connection is made with the Nacosari mately with the trend of the range and dipping at FIG. 1. Map showing physiographic regions of Arizona. Range system of Nevada and Utah, and is consid­ Railroad to Cos, and at Naco with the Cananea, generally moderate angles toward Sulphur Spring ered by him as exhibiting the same prevailing type Yaqui River and Pacific Railroad to Cananea, thus Valley. The slopes of these hills are comparatively the Colorado Chiquito from those of the Gila. of orographic structure. He states that his exam­ bringing the new smelting town of Douglas within smooth, although the occurrence of a hard fossil- These cliffs are well shown at the southwestern inations "have demonstrated no anticlinal struc­ reach of the important mines at Nacosari and iferous limestone in the middle of the generally^ are­ edge of the Mogollon Mesa, where tliey form an tures, except as minor features.' ' The usual Cananea in the State of Sonora. naceous group has occasioned a conspicuous and abrupt scarp from 1000 to 2000 feet in height, structure is monoclinal, demonstrably due to fault­ persistent cliff of erosion. TOPOGEAPHY. overlooking the Tonto basin and facing the ing in the Chiricahua and Final ranges, and pre­ Southwest of the divisional line Paleozoic and Mazatzal and Ancha ranges. From Fort Apache sumably so in all the others." With this con­ MULE MOUNTAINS. older rocks prevail. These are generally more eastward to the New Mexico line the plateau clusion the observations embodied in the present As the boundaries of the Bisbee quadrangle resistant to erosion and more heterogeneous in boundary is less distinct. Vast accumulations of folio accord. have been determined without regard to physio­ character than the Mesozoic beds, and have a far volcanic rock have obscured the plateau surface As far as can be gathered from existing descrip­ graphic or geological unity, it is desirable that a more complicated structure. Their erosion has and erosion has partly destroyed its continuity. tions the greater number of the ranges consist brief general account of the topography of the Mule consequently produced a more rugged and less The San Francisco, Mogollon, Blanca (White), and mainly of Paleozoic sandstones or quartzites and Mountains should precede the' more detailed regular topography. These older rocks have their Escudillo mountains are described by Gilbert as vol­ limestones, resting with marked unconformity description of a smaller area. greatest development west of Bisbee, and it is here canic masses resting upon the general plateau sur­ upon pre-Cambrian schists and granites. The Topographically the Mule Mountains are less that the range is highest and broadest. With the face. Describing this surface Dutton, in his Tertiary extent to which this ancient basement composes imposing than the neighboring Huachuca and gradual disappearance of the Paleozoic rocks to the History of the Grand Canon District, says: the mass of a given range is dependent upon the Chiricahua mountains, lacking both the striking northwest and southeast, the Mesozoic rocks make elevation of the latter and the amount of subse­ linear plan and the bold serrate form of these up an increasing part of the mountain mass and Its strata are very nearly horizontal, and with the quent degradation which it has undergone by ranges. They are a compact group of ridges and the general height of the range diminishes. Thus exception of Cataract Canon and some of its tributaries erosion. The Paleozoic and pre-Cambrian rocks peaks, and, like other mountain masses in thisMount Ballard, one of the peaks of and less uniform structures, resulting from trans­ beds. The nearest remnant of similar beds is many Region of Arizona. It can not be sharply distin­ Escabrosa Ridge, 1^ miles southwest of Mule Pass verse faulting, complex folding, and irregular miles away. The butte owes its preservation to a mantle guished, at least without further investigation in and 2^ miles west of Bisbee. The general height intrusions, have deeply impressed their own char­ of basalt which came to the surface near the center of its summit. It is an important factor in the evidence the field, from the Mountain Region, but the of the range decreases both northwest and south­ acter upon the topography. upon which rest th^ deductions concerning the great boundary between the two may provisionally be east of Mule Pass. About 5 miles northwest of With this preliminary survey of the topography erosion of this country. taken as a curved line extending from Nogales on the pass the road to Tombstone enters more open of the Mule Mountains as a whole, attention may

§ now be given more particularly to the Bisbee quad­ about halfway between Black Gap and Gold Hill; DUMBLE, E. T. Notes on the Geology of Southeastern Glance conglomerate, which marks the base of the Arizona. Trans. Am. Inst. Min. Eng., vol. 31, 1902, pp. Cretaceous sediments. It is exposed also by the rangle, which* embraces practically the southeastern thence it turns northwestward across the open basin 36-715. half of the range. just north of Black Gap, and coincides with the Describes particularly the Cretaceous deposits in the Mule Mountains and rosion of the overlying Cretaceous in the upper The two-fold topographic division of the Mule crest of Escabrosa Ridge as far as Mount Ballard. names them the Bisbee beds. Estimates their total thickness at about 3000 part of Soto Canyon, east of Juniper Flat. feet. Notes the occurrence of Carboniferous limestone and suggests that Mountains, just described, is well shown within the From this peak it swings northeastward across Devonian is also represented. Correlates the quartzite (Bolsa quartzite) Along Escabrosa Ridge, northwest of Mount underlying the Paleozoic limestones with the quartzite of the Dragoon Moun­ quadrangle itself. Northeast of a line drawn about Mule Pass to the broad ridge known as Juniper tains (Dragoon quartzite) . Refers to it as pre -Devonian. Notes the occurrence Martin, the Pinal schist is well exposed, some­ of mica-schists, to which he assigns a thickness of 800 feet. States that they times forming the crest of the ridge and sometimes half a mile northeast of Tombstone Canyon, Mule Flat. The country lying northeast of this tortuous rest upon granite, although in some places an intrusive porphyry is said to Pass, and Bisbee, and extending southeastward to water-parting drains into Sulphur Spring Valley, intervene. capped by outliers of Paleozoic strata. It also Gold Hill, there is, broadly speaking, a monoclinal and during the wet season such water as is not GENERAL GEOLOGY. extends down the southwest slope of the ridge, as ridge composed of Mesozoic strata, with general evaporated on the way reaches the Agua Prieta, a in Moore and Bolsa canyons, but is there inter- PKELIMINABY OUTLINE. northeasterly dip, resting upon pre-Cambrian schist headwater tributary of the Yaqui River. The ected by an elaborate network of dikes and faults. and intrusive granite-porphyry. The back of this country southwest of the divide has a similar inter­ The fundamental rocks of the Bisbee quadrangle The most southern exposures of the schist are ridge is deeply furrowed by numerous consequent mittent and partly underground drainage into the are crystalline schists of pre-Cambrian age, sep­ in a few small fault blocks near the mouth of intermittent streams flowing northeastward into San Pedro. arated by a profound unconformity from the over­ Escacado Canyon, 1^ miles northwest of Don Sulphur Spring Valley. When considered in lying Paleozoic beds. The latter comprise a basal Luis. CLIMATE AND VEGETATION. detail, however, the strata composing the ridge are Cambrian quartzite 430 feet in thickness, succeeded In general the main exposed area of Pinal schist found to be folded and to be cut by several faults. The climate of Bisbee offers no marked excep­ by over 4500 feet of limestones representing por­ may be described as limited on the southwest partly Southwest of this dividing line are the Paleozoic tion to the prevailing aridity of central and south­ tions of Cambriaiij, Devonian, and Carboniferous by passage beneath the unconformably overlying and pre-Cambrian rocks. On the whole, the Paleo­ ern Arizona. Owing to the altitude of the town, time. The Ordovician and Silurian systems, so Bolsa quartzite, but chiefly by faults and igneous zoic beds have a northwest-southeast strike, which 5300 feet, a temperature of 100 degrees is rarely far as known, have no lithological representation intrusions, and as bounded on the northeast by the finds topographic expression in Escabrosa Ridge reached in summer. The winter temperature in the quadrangle. irregular line defining the base of the Cretaceous and in the chain of hills extending past Black Gap seldom falls below 15 degrees, and the annual At the close of the Carboniferous period the beds, under which the schist extends for an to Gold Hill. On the southwest slope of Escabrosa mean is about 60.5 degrees. As shown by the rocks of the Bisbee quadrangle were deformed by unknown distance as the eroded basement upon Bidge numerous faults and dikes of porphyry, reports of the United States Weather Bureau from faulting and folding and were cut by intrusions of which these Mesozoic sediments were laid down. in general parallel with the strike, have cooper­ 1891 to the end of 1900, the average annual pre­ granitic magma. The principal mineralization of The Pinal schist has a typical schistose structure. ated in maintaining the dominant northwest-south­ cipitation is about 17 inches, so that the aridity, the district probably dates from this time of revo­ The planes of schistosity are usually more nearly east trend of the main ridge. Inspection of the while pronounced, is not extreme. The hottest lutionary disturbance. The region as a whole was vertical than horizontal, and are so contorted and maps, however, shows that the complex deforma­ months are June and July. The greater part of elevated above sea level and subjected to erosion so variable in dip and strike from point to point tion of this portion of the quadrangle has led to a the annual precipitation falls during July and until the beginning of the Cretaceous period. as to preclude, in the present stage of regional much more irregular topography than that char­ August as heavy showers, which are often very During the Cretaceous the land again sank denudation, any unraveling of general pre-Cam­ acterizing the Mesozoic terrane to the northeast. local in extent and of short duration. Occasional beneath the sea, and over 4500 feet of sandstones, brian structure. The dominant trend of the Southeast of Gold Hill the general topographic showers of rain and flurries of snow may occur at shales, and limestone, representing the earlier part schistosity appears to be about NNE.-SSW., but division just described does not exist. The Paleo­ other times during the year, but they are rarely of this period, were accumulated. wide departures from this direction are encountered zoic rocks are here for the most part buried sufficient to tint with green the brown landscape or Subsequent elevation brought these sediments on every hand. The schists sometimes exhibit an beneath the Cretaceous beds, which extend farther to aid in the transportation of detritus from the above sea level and exposed them to erosion. The inconspicuous banding which is not always parallel to the southwest than elsewhere in the quad­ mountain slopes into the valleys. The quadran­ quadrangle contains no rocks of Tertiary age and with the planes of schistosity and is suggestive of rangle. gle contains no permanent streams and but few there are no known facts from which to determine an original bedded structure. perennial springs. the exact date of the post-Cretaceous uplift. It Neither the original base of the rocks which have SULPHUR SPRING VALLEY. Junipers and oaks of considerable size were was accompanied or followed by faulting and been transformed by metamorphism to the Pinal Probably the most striking topographical feature formerly abundant in the quadrangle, particularly folding. schist nor the present bottom of the latter terrane apparent in the map of the quadrangle is the sharp on Juniper Flat and Escabrosa Ridge, but with During the Quaternary and probably during a is exposed in the Bisbee quadrangle. Accordingly contrast between mountain and plain a contrast the demand for firewood these have disappeared. part of the Tertiary the higher parts of the Bisbee the thickness of the Pinal formation prior to recrys- which, while in .no way exaggerated, is perhaps Such trees as still grow on some of the northern quadrangle have been undergoing erosion, their tallization and the depth to which the schists now even more striking in a map than on the ground; hill slopes are little more than bushes. Prior to waste accumulating in the flat-floored valleys that extend must remain unknown. for one who travels through the arid portions of 1893 oak trees stood in the streets of Bisbee and surround the Mule Mountains. Lithology. The Pinal schist varies in color from the neighboring hill slopes were dotted with shrubs, New Mexico and Arizona usually sees the same DESCRIPTION OF THE EOCKS. light to dark gray, often with a slight tinge of green. feature again and again long before he reaches the but this vegetation was destroyed soon after the The cleavage is imperfect, and the surfaces have Pre-Cambrian Metamorphic Rocks. Mule Mountains. In the eastern part of the quad­ introduction of the matte process in the Copper commonly a satin-like sheen. In texture and gen­ rangle the floor of Sulphur Spring Valley, here Queen smelter, by the resulting sulphurous fumes. SCHIST. eral appearance the schist is monotonously uniform. rising gently toward the southwest from the valley Once each year, just after the summer rains, the Name. In the Globe folio, the name Final It is very fine grained throughout, and the naked axis, with a grade of less than 100 feet to the mile, country awakes for a brief period from its long schist was applied to the fundamental crystalline eye can rarely distinguish any mineral constituents ends abruptly at the Mule Mountains, whose drought to a belated spring. Grasses wave over metamorphic rocks of the Final Range. These other than small glittering scales of sericite and northeast front rises with an average grade eight the hill slopes and gay-colored flowers nod among were shown to be essentially quartz-muscovite- or occasional granules of quartz. times that of the valley slopes. the rocks. But this change in the face of the quartz-sericite-schists derived from arenaceous sedi­ The microscope shows that the essential con­ A slight increase in the inclination of the plain country is as transient as it is beautiful, and the ments, and to be separated from the oldest Paleo- stituents are quartz and sericite, which form a is noticeable near the mountains, owing to the fresh verdure soon fades into the neutral tints of zoic rocks by a profound unconformity. The crystalline aggregate of minute interlocking grains, accumulation along their front of coarser fluvia- hopeless aridity. Final Range lies about 90 miles north of the and tiny foliated wisps. The sericite shows a tile material in low, coalescing detrital fans. This Bisbee quadrangle, and no occurrence of Final tendency toward arrangement in parallel bands increase, however, is not enough to detract mate­ PREVIOUS STUDIES IN THE AEEA. schist has yet been identified within the interven­ and thereby gives to the rock its imperfectly fissile rially from the abrupt change in slope, which The first attempt to describe the geological envi­ ing country. Nevertheless, the lithological simi­ character. With these preponderant minerals are corresponds in general with the boundary between ronment of the Bisbee copper ores was that of larity' of the schists of the Pinal Range and of the commonly associated a few small prisms of tourma­ the Quaternary wash and the older rocks. The Wendt, in 1887, which was followed thirteen years Mule Mountains, and their identical relation to the line up to a quarter of a millimeter in length, difference in altitude between the lowest part of later by a more comprehensive account by Doug­ great unconformity at the base of the Paleozoic, occasional red garnets of about the same diameter, Sulphur Spring Valley included within the quad­ las. Both of these papers, however, touch on the are considered to justify the application of the a few nests or shreds of chlorite, small crystals of rangle and the highest point in the Mule Mountains geology and structure of the Mule Mountains in the name Pinal schist to the fundamental schistose zircon, and granules of magnetite or ilmenite. An is about 3300 feet. briefest way, being concerned mainly with the ore rocks of the Bisbee quadrangle. occasional grain of sodium-calcium feldspar, prob­ bodies and with the process of ore extraction. Distribution and general structure. The Pinal ably oligoclase, can be microscopically detected ESPINAL PLAIN. Dumble's reconnaissance notes published in 1902, schist is the ancient crystalline foundation upon among the quartz grains which make up most of In the southwestern part of the quadrangle although necessarily fragmentary, are the first step which rest all the Paleozoic and younger sedi­ the rock. Espinal Plain, which surrounds the town of Naco toward any general knowledge of the broader ments of the region, and through which have Amphibole was not observed in any of the speci­ and is really an embayment of the San Pedro Val­ geological features, and to him is due the first broken the granite and porphyries exposed in mens studied, and biotite is certainly a rare con­ ley, exhibits a similar striking contrast to the recorded recognition of the extensive Cretaceous various parts of the district. It is probable that it stituent, although it was noted in a bleached and mountains north of it. To the east of the plain deposits of the Bisbee region. underlies the entire quadrangle, but for the most decomposed state in a single thin section. the change is less marked, as the part of the Mule The papers just referred to, with two other works part it is buried beneath hundreds or thousands of Origin. The general character of the schists in Mountains just east of Gold Gulch, composed of of a general nature, which have been drawn upon feet of later rocks. At present it is exposed only the Bisbee quadrangle indicates that they were Mesozoic conglomerate, is well worn down by ero­ for historical data, are included in the following in the northwest quarter of the quadrangle, where at one time arkosic sands or silts. Their meta­ sion. Espinal Plain is not entirely a construc­ brief list of publications: the beds which formerly covered it have been morphism has been more uniform than in the tional plain, but is in small part floored by Meso­ List of publications on the Sisbee district. stripped oif by erosion. Pinal Mountains of the Globe district, without the zoic and Paleozoic rocks that have been eroded to HINTON, R. J. The Handbook of Arizona. San Francisco The largest area of Pinal schist, if interruptions development of any such coarsely crystalline phases the general slope of the plain surface. and New York, 1878. due to intrusive bodies of porphyry be disregarded, as are there found. This difference is undoubtedly General description and early history of region about the Mule Mountains. is that which underlies the town of Bisbee. This connected with the absence of pre-Cambrian gran­ Records the then recent discovery of ore in these mountains. DRAINAGE OF THE AREA. area, which, so far as present exposures go, is itic intrusives in the Mule Mountains and their HAMILTON, PATRICK. The Resources of Arizona. First Two river systems compete for the drainage of edition, Prescott, Ariz., 1881. Second edition, San Francisco, divided by the porphyry mass of Sacramento Hill, abundance in the Pinal Range. Much of the the Bisbee quadrangle. One is the northward- 1883. Third edition, San Francisco, 1884. extends southeastward from the town about 3 miles metamerphism of the Pinal schist in the Globe flowing San Pedro, whose waters find their way Contains notes of the early history of mining near Bisbee. and finally disappears beneath the Cretaceous rocks quadrangle is due to the obvious contact action of through the Gila and Colorado rivers into the Gulf WENDT, ARTHUR F. The Copper Ores of the Southwest. in Mule Gulch. Northwest of Bisbee the area large intrusive masses. While it can not be said Trans. Am. Inst. Min. Eng., vol. 15, 1887, pp. 25-77. of California. The other is the southward-flowing Sketches briefly the geological occurrence of the ores. Describes the latter becomes much broader and the Pinal schist forms that concealed bodies of intrusive rock have had Yaqui River, which also enters the Gulf of Cali­ as filling fissures and caves in Carboniferous limestone, and concludes that most of the slope between Tombstone Canyon and no part in the recrystallization of the Pinal forma­ they were originally deposited as carbonates and oxides, and not derived from fornia after traversing the Mexican State of Sonora. sulphides by oxidation practically in situ. the crest of Escabrosa Ridge. It is the rock in tion of the Mule Mountains, this process seems to The divide between these two drainage areas enters DOUGLAS, JAMES. The Copper Queen Mine. Trans. Am. which Brewery Gulch and Dubacher Canyon, north be more nearly a simple case of what is known as the quadrangle at boundary monument No. 91 and Inst. Min. Eng., vol. 29, 1900, pp. 511-546. and east of Bisbee, have been excavated, and near regional metamorphism. Sketches the history of the mine and describes the character and geological runs north across Espinal Plain to a low saddle occurrence of the ores. Discusses the origin of the ore bodies. the heads of these ravines it passes beneath the Age and correlation. The crystalline Pinal schist which was probably originally a sedimentary rock of a mile west of* the center of town the quartzite, Distribution and general stratigraphy. Like the northwest from Abrigo Canyon exhibits the gen­ but whose original structure has been nearly oblit­ which has been quarried for silica, is well exposed Bolsa quartzite, the Abrigo limestone occurs prin­ eral lithological character of the Mount Martin erated by metamorphism, underlies Cambrian beds as the basal formation of the faulted syncline of cipally in the northwestern part of the quadrangle, section. In Abrigo Canyon, however, the soft in which the ordinary change from loose cross- Paleozoic rocks, to be later described. Half a mile although a few small areas are found within the sandy limestones below the white quartzite are bedded sands to hard sandstones or quartzites con­ west of the quarry, and separated by a great fault attenuated belt of Paleozoic rocks extending south­ represented by calcareous grits which are darker stitutes the only noticeable alteration. The Cam­ from the syncline just referred to, is the most typi­ eastward past Gold Hill toward Glance Creek. and harder than the corresponding beds farther brian beds rest with a basal conglomerate upon the cal and instructive exposure of the Bolsa quartzite The most satisfactory occurrence, and the only north, and these grits, sometimes associated with eroded edges of the contorted schists. The Final to be found in the quadrangle. The beds, with a one in the quadrangle where the entire sequence hard, dark-gray, dolomitic beds containing abun­ schist is therefore not only pre-Cambrian but is total thickness of 430 feet, are continuously exposed of the beds from base to top may be studied in a dant quartz grains, as just north of Don Luis, con­ separated from the Cambrain strata by profound in the line of strike for a distance of a little less single continuous exposure, is that of the Mount tinue to characterize the upper part of the Abrigo unconformity. This unconformity, considered in than a mile along the northeast slope of Mount Martin section (see fig. 4), a mile and a half west limestone as far as the formation can be traced to connection with the train of geological events Martin. They rest with a very conspicuous uncon­ of Bisbee. the southeast. They are rather hard, thin-bedded, implied by the complete metamorphism of Final formity upon the pre-Cambrian schists, and dip to As measured in this section the Abrigo limestone sandy limestones, usually dark gray in tint, and schists prior to the deposition of the earliest Cam­ the southwest at an angle of about 25 degrees. is 770 feet in thickness. It rests conformably occasionally rusty on weathered surfaces. They brian sediments of the region, presents no less They are conformably overlain by the Abrigo upon the Bolsa quartzite and is overlain by the frequently show cross-bedding, particularly just vividly to the imagination "the long result of (Cambrian) limestone, succeeded by the Martin Martin limestone (Devonian). The beds strike north of Don Luis. time" than do all of the up-piled beds of the Pale­ (Devonian) and Escabrosa (Mississippian) lime­ nearly northwest-southeast, and dip southwest at Very fissile, greenish-yellow, calcareous shales, ozoic. There can be no question that the Final stones, the last named forming the summit of an angle of 25 degrees. often showing casts of worm borings and glisten­ schist is vastly older than the Cambrian sedi­ Mount Martin. As this section is a typical one Many smaller areas of the Abrigo formation ing with minute scales of mica, are generally a ments. not only for the Bolsa quartzite but for the occur along the crest of Escabrosa Ridge, com­ characteristic feature of the lower half of the If, as is not improbable, the Final schist is the overlying Paleozoic limestones, it will be fre­ monly bounded on two or more sides by faults, or Abrigo formation where this part is exposed. equivalent of the "Vishnu series" of Walcott in quently referred to in the following pages and by dikes of granite-porphyry. The most extensive Such beds usually form smooth topographic slopes the Grand Canyon of the Colorado, then it is also may be conveniently designated the Mount Martin exposures, however, are found on the southwest and weather to fragments often superficially resem­ much older than the supposed Algonkian rocks section. slope of the ridge, where the Abrigo limestone bling those resulting from the disintegration of the represented by the "Chuar and Unkar terranes," Between Mount Martin and the western edge of underlies a practically continuous area about a mile pre-Cambrian schists. which in that great gorge are found to overlie the the quadrangle are many small areas of the Bolsa in width and 4 miles in length, stretching north­ Age and correlation. The fossils collected from Vishnu schists with conspicuous unconformity. quartzite bounded on one or more sides by faults. west from Abrigo Canyon to about a mile beyond the Abrigo limestone, comprising trilobites, small Furthermore, Fowell and Walcott describe the As may be seen from the geological map, all the Moore Canyon. The boundaries of this area are lingulas, and pteropods of the genus Hyolithes, "Grand Canon schists," or "Vishnu series," as exposures of the Bolsa quartzite occur in the north­ in most cases faults or intrusive contacts. The were submitted to Dr. Charles D. Walcott, who in part metamorphosed sediments, and the Final west quarter of the Bisbee quadrangle. The for­ prevailing strike of the beds is northwest-southeast, reported that they are middle Cambrian, indicating schist of the Globe region was certainly derived mation undoubtedly underlies other portions of the and they dip in general to the southwest. a fauna closely resembling that of the middle Cam­ from ancient sediments by metamorphism? area studied, but is there buried beneath younger As the Abrigo limestone is more readily eroded brian of Texas. If, therefore, the original definition of the Algon­ beds. The present distribution of the exposed than the granite-porphyry, Bolsa quartzite, and DEVONIAN SYSTEM. kian as including all pre-Cambrian sedimentary areas is determined by deformation and erosion, younger Paleozoic limestones, the larger areas of rocks be accepted, the Final schists belong in that not by original deposition. this rock are found to be associated with topo­ MARTIN LIMESTONE. period, which must then be considered as embrac­ Lithology. The Bolsa quartzite is constant in graphic features of but relatively slight prominence. Name. The Martin limestone is named from ing rocks above and below the most profound its lithological character and is readily recognized The area just described as stretching northwest­ Mount Martin, on Escabrosa Ridge, where the unconformity known in Arizona. In view of this wherever it occurs within the quadrangle. ward from Abrigo Canyon is characterized by moderately thick, usually dark-gray beds of this fact, it seems best, in the absence of definite cor­ The base of the formation is exposed at many gentle slopes, broad, open arroyos, and low ridges, formation are typically developed and well exposed. relation, to refer to the Final schist simply as pre- places along Escabrosa Ridge. It is invariably in marked contrast with the more rugged topog­ Distribution and general stratigraphy. In the Cambrian, leaving future investigation to determine marked by a bed of conglomerate from 6 inches to raphy of the main Escabrosa Ridge. Mount Martin section the Martin limestone attains wrhether the Algonkian is to be represented in a foot in thickness, resting upon the eroded edges Lithology. The Abrigo limestone is distin­ a thickness of 340 feet. The beds overlie the Arizona by the Grand Canyon series, or by the of the pre-Cambrian schists. Most of the pebbles guished from the other calcareous formations of the Abrigo (Cambrian) limestone and underlie the Vishnu series, or by both of these series sepa­ of this basal conglomerate are composed of white local Paleozoic section by its prevailing thin bed­ Escabrosa (Mississippian) limestone, both relations rated by an unconformity apparently as pro­ vein quartz and are rarely over 3 inches in diame­ ding and particularly by a conspicuous laminated being those of apparent conformity. found as any described in geological literature. ter. This conglomerate is overlain by hard pebbly structure produced by alternation of thin, irregular Other small areas of the Martin limestone are Paleozoic Sedimentary Rocks. grits in beds from 10 to 20 feet in thickness, the sheets of chert with layers of gray limestone (see involved in the faulted structure of Escabrosa change from conglomerate to grit being as a rule fig. 5). The layers of limestone may be 2 or 3 Ridge, from the northwest corner of the quadrangle GENERAL STATEMENT. not very definitely marked. The scattered peb­ inches in thickness, while those of chert are usually to Don Luis and thence southeastward past Black The Paleozoic rocks of the Bisbee quadrangle bles in these thick-bedded grits are usually white less. This cherty lamination is eminently charac­ Gap and Gold Hill to Glance. The formation is are divisible into five formations. At the base, quartz, but their matrix frequently contains teristic of the Abrigo limestone in the Mule Moun­ typically developed noith of Moore Canyon, being resting upon the Final schist, is the unfossiliferous abundant small fragments of pink feldspar mingled tains and serves as a ready means of identifying exposed from top to base at several localities. It Bolsa quartzite. Overlying the quartzite is the with the predominant quartz grains. Cross-bed­ the beds belonging to this formation within the is also well exposed in the vicinity of Abrigo Can­ Abrigo limestone, carrying middle Cambrian fos­ ding is often a conspicuous feature in the lower various fault blocks into which the region is dis­ yon, but the stratigraphic relations are here com­ sils. Succeeding the Abrigo is the Martin lime­ part of the formation. The pebbly grits in turn sected. Chert also occurs in occasional irregular plicated by overthrust faulting. stone, of Devonian age, wrhich in turn is overlain pass upward into thinner bedded, more vitreous, bunches in the Devonian and Carboniferous lime­ The conspicuous turreted crag overlooking Main by the Carboniferous (Mississippian) Escabrosa fine-grained quartzites showing no feldspathic stones of the Bisbee quadrangle, but never in the street in Bisbee, known as Castle Rock, is com­ limestone. The youngest of the Paleozoic forma­ material, which are conformably overlain by the form of the thin, more or less anastomosing sheets posed of Martin limestone. Extending southwest- tions is the Naco limestone, which overlies the Abrigo limestone. peculiar to the Cambrian Abrigo limestone. ward from Castle Rock to Escacado Canyon and Escabrosa and belongs in the Pennsylvanian Age. and correlation. As no fossils have been The beds are commonly from 1 to 2 feet in thence southeastward to Glance is a curved chain series of the Carboniferous. found in the Bolsa quartzite, its exact geological thickness. Their dominant color as seen in large of small areas of this limestone, which, as will be age is not directly determinable. It will presently exposures is dark greenish-yellow, whereas the pre­ more fully shown later, form part of a much CAMBRIAN SYSTEM. be shown, however, that the Bolsa formation is vailing tint of the overlying Martin limestone is faulted syncline. Although the areas are separa­ BOLSA QUARTZITE. conformably overlain by the Abrigo limestone, dark gray, and that of the still higher Escabrosa ted by faults, the beds dip and strike in conform­ Name. The name Dragoon quartzite has been which contains a middle Cambrian fauna. It is and Naco limestones white or light gray. ity with the general synclinal structure. Those applied by E. T. Dumble to some pre-Devonian thus, without much doubt, the stratigraphic In the typical Mount Martin section the Bolsa between Castle Rock and Escacado Canyon dip to arenaceous beds, about 400 feet in thickness, occur­ equivalent of the Tonto\ sandstone of the Grand quartzite is immediately overlain by about 40 feet the southeast, while those between Escacado Can­ ring in the Dragoon Mountains. Canyon section, considered by Walcott as also of thin-bedded, very cherty limestone, which breaks yon and Glance dip to the northeast. It is possible that the so-called Dragoon quartz­ included within the middle Cambrian, the lower up, on weathering, into thin rusty plates. Above Owing to its medial position within the Paleo­ ites of the Dragoon and of the Mule mountains Cambrian being there represented by the uncon­ this occur a few beds of gray limestone, up to 2 zoic sequence and its comparative thinness, 300 to are, as Dumble supposed, stratigraphically the formity between the Tonto and the Grand Canyon feet in thickness, alternating with fissile, yellowish, 350 feet, the Martin limestone is more generally "same, but this correlation can not be regarded as series. It is possibly the equivalent of the lower calcareous shales-and with laminated cherty beds distributed and is oftener present in its entirety established. For this reason the name Dragoon part of the thicker and more varied Apache group such as have just been described. The upper 100 than are the overlying or underlying beds. It quartzite has been abandoned as applied to the of the Globe district in central Arizona, about 110 feet of the formation is made up -of rather soft, is rarely topographically conspicuous, however, basal sedimentary formation of the Bisbee quad­ miles north-northwest of the Bisbee quadrangle, sandy, thin-bedded, gray limestones, with one bed usually outcropping on slopes below cliffs of Esca­ rangle and Bolsa quartzite adopted in its stead. and also correlated provisionally in the Globe folio of harder gray limestone 6 feet in thickness about brosa limestone and above lowlands floored with The later designation is derived from Bolsa Can­ with the Tonto group. 40 feet from the top. The upper limit of the the-Abrigo limestone. yon, on the southwest side of Escabrosa Bidge, In the Mule Mountains the absence of Algon­ Abrigo formation is defined in the Mount Martin Lithology. The beds most characteristic of the where these beds are well exposed. kian beds equivalent to the Grand Canyon group section by a bed of pure white quartzite about 8 Martin formation are dark-gray, hard, compact Distribution and general stratigraphy. The renders the unconformity at the base of the mid­ feet thick. limestones which are generally well provided with principal exposures of the Bolsa quartzite are in dle Cambrian even more pronounced than in the This quartzite is a persistent stratum and is fossils. Small brachiopods (Atrypa reticularis and Escabrosa Ridge, west of Bisbee. In the north­ Grand Canyon. At Bisbee the Bolsa quartzite always found immediately underlying the Martin Spirifer hungerfordi) of rounded outline are par­ east corner of the quadrangle this formation is rep­ rests directly upon the Final schist, which is limestone, which carries Devonian fossils. Its ticularly abundant in some of the beds and give to resented by small residual outlier's resting here and regarded as probably the equivalent of the Vishnu thickness, however, is variable and it sometimes the weathered surfaces of the limestone a nodular there along the crest of the ridge upon the pre- schist of the Grand Canyon section, although grades downward into the upper sandy limestones appearance, which in the Bisbee quadrangle is Cambrian schists. These remnants of once con­ further work in Arizona is necessary to establish of the Abrigo formation. It apparently records peculiar to the Martin formation. A few of the tinuous strata become larger toward the southeast, this correlation. the consummation of an increasing supply of beds are richly provided with corals, some of which and near Bisbee the quartzite makes up a consider­ sandy sediments during the later phases of the weather out as distinct and often beautifully silici- able part of Escabrosa Ridge. Owing to the prev­ ABRIGO LIMESTONE. deposition of the Abrigo limestone, and contrasts fied fossils, while others make rather ill-defined, alent faulting, however, the ^olsa quartzite is not Name. The Abrigo limestone is named from with the more purely calcareous beds of the over­ white dendritic blotches in the dark limestone, pro­ found in extensive areas nor in continuous belts of Abrigo Canyon, 3 miles southwest of Bisbee, where lying Devonian formation. ducing an appearance that experience has shown to more than a mile in length. About three quarters the beds composing the formation are well exposed. The large area of Abrigo limestone stretching be a local criterion of some value in identifying Bisbee. small masses of the Martin limestone when they structure near Abrigo Canyon and will be fully ing past Glance to within a mile and a half of the Age and correlation. All of the fossils collected are faulted in among other beds. described on later pages. The upper part of the Mexican boundary. The main area, between Bis­ from the Escabrosa and Naco limestones were sub­ Associated with the preponderant dark lime­ Escabrosa passes without any stratigraphic break bee and Gold Gulch, partly covered by the Cre­ mitted to Mr. George H. Girty, who reports that stones are occasional beds of lighter hue, and or marked lithological change into the overlying taceous Glance conglomerate, constitutes the inner three well-marked Carboniferous faunas are repre­ sometimes calcareous shales of a decided pinkish Naco limestone. These two formations were dis­ Paleozoic member of the faulted syncline which sented (see illustration sheet 2). One of these, tint. These shales, which flake and crumble on tinguished primarily upon paleontological evidence, has been referred to several times and which will characteristic of the Escabrosa limestone, is of exposure, are well exposed in the saddle just north­ and they have accordingly been mapped in dif­ subsequently be shown to have a very important Mississippian age; the other two, from the Naco east of Mount Martin, where they carry abundant ferent colors but with no definite dividing line connection with the great copper deposits of the limestone, are of Pennsylvanian age. The Missis­ characteristic Devonian fossils. They occur also except in the case of faults. There are, indeed, district. Although much disturbed by faulting, sippian fauna is the same as that which is widely in several of the other areas of the Martin lime­ certain lithological differences between the Esca­ the beds generally conform to the dominant syn­ distributed in the West, and has generally been stone, particularly on the southwest slopes of brosa limestone and the Naco limestone, as will be clinal structure, dipping southeastward near Bisbee recognized as that which characterizes the Waverly Escabrosa Ridge, but owing to their softness are pointed out when the latter is described, but it is and then swinging around in a rather sharp curve group of Ohio. A few characteristic forms are seldom conspicuous except where revealed by pros­ only after an intimate familiarity with the beds is until they dip to the northeast near Black Gap. Rhipidomella thiemei, Leptwna rhomboidalis, Cho- pecting pits and tunnels. They belong in the gained that these lithological criteria can be utilized The masses forming the summit of Gold Hill and netes loganensis, Spirifer centronatus, Spirifer pecu- lower half of the formation. as a basis of separation. They would not in them­ the other areas to the southeast owe their positions liaris, Syringothyris carleri, Athyris lamellosa, The upper limit of the Martin limestone is not selves have suggested the twofold division of the to faults which have thrust them bodily over Cre­ Eumetria marcyi, Myalina keokuk and PhiUipsia always sharply defined. In general it corresponds Carboniferous limestones here adopted. taceous beds, as will be described in the section on peroccidens. This Bisbee fauna probably repre­ with the decided change from the dark compact The thickness of the Escabrosa limestone in the geological structure. sents the earlier half of Mississippian time, includ­ limestones characteristic of this formation to the Bisbee quadrangle can not be determined with the The Naco limestone conformably overlies the ing the Kinderhook and Osage divisions. nearly white granular limestones, made up largely same accuracy as that of the Devonian and Cam­ Escabrosa limestone, as may be well seen at several The earlier of the two Pennsylvanian faunas is of crinoid stems, which characterize the Escabrosa brian limestones. Although the overlying Naco points along Escabrosa Ridge southeast of Mount largely composed of species \\hich characterize the formation. The actual plane of division is, how­ limestone has been eroded from the summit of Martin, and pa,rticularly in the excellent exposures Pennsylvanian faunas of the Mississippi Valley. ever, rarely visible owing to the tendency of the Mount Martin, there is good reason to conclude a mile due north of Don Luis (see fig. 3), where The later of the two Pennsylvanian faunas com­ Escabrosa limestone to form cliffs and the conse­ that the Escabrosa limestone is still present in this the rather thin beds immediately above and below prises many species as yet undescribed. Very few quent accumulation of talus over the contact. section in very nearly its original thickness, which the plane of division are continuously exposed for of the species have exact representatives in the Even when no detritus conceals the relation of measurements and calculations give as approxi­ nearly a mile along a steep slope. The upper limit Mississippi Valley, and few, if any, are found in the two formations there may be an intermediate mately 800 feet. Another section just west of of the Naco formation is a rather irregular surface of the earlier Pennsylvanian fauna of the Bisbee zone 10 to 20 feet in thickness which contains Black Gap, where apparently the whole of the erosion upon which the basal conglomerate of the quadrangle. A few species are suggestive of the no characteristic fossils and which it is impossible Escabrosa limestone is represented in conformable Cretaceous Bisbee group was deposited. The orig­ Aubrey limestone of the Grand Canyon section, to assign with confidence, on purely lithological sequence between the Martin and Naco limestones, inal thickness of the formation is thus unknown, while others suggest the Permo-Pennsylvanian of grounds, to either the Martin or the Escabrosa affords a thickness of a little more than 600 feet. but it undo abtedly greatly exceeds that of any California. The whole fauna is closely related to 'limestone. A third section was measured 1} miles south of other member of the local Paleozoic section. that of the limestones of the Hueco Mountains in The beds of the Martin limestone are usually Bisbee, near the Whitetail mine, and intermediate Measured sections in the Naco Hills show that the western Texas, and is very different from the so- less than 4 feet in thickness. They are thicker, in position between the two already referred to. formation as there exposed has a present thickness called Permo-Pennsylvanian of the Mississippi on the whole, than those of the underlying Abrigo This afforded a minimum thickness of 775 feet. of at least 1500 feet and probably of as much Valley. Some of the characteristic Pennsylva­ limestone, but thinner than those of the overlying It thus appears that the Escabrosa limestone as 2000 feet. To this there must be added nian forms from Bisbee are Fusulina cylindrica, Escabrosa limestone, next to be described. has a maximum thickness of about 800 feet and an unknown thickness removed by erosion and Chwtetes milleporaceus, Derby a crassa, Productus Age and correlation. Several collections of fos­ probably thins out toward the southeast to about an unexposed portion concealed by Quaternary semireticulatus, Productus injlatus (?), Productus sils from the Martin limestone were submitted to 600 feet. For general purposes 700 feet will be deposits. Unless there are important faults .which nebraskensis, Spirifer cameratus, Seminula sub- Prof. Henry S. Williams, of Yale University. He taken as the average thickness of the formation. have escaped the careful examination given to the tilita, Spiriferina kentuckyensis, Hustedia mor- reports that they represent a meso-Devonian fauna Lithology. The characteristic rocks of the Esca­ synclinal area of Naco limestone just south of moni. finding its nearest analogues in the Devonian brosa formation are rather thick-bedded, nearly Bisbee, 3000 feet is a very moderate estimate for The close relationship, pointed out by Mr. Girty, faunas of Iowa and Russia. A few of the more white to dark gray, granular limestones, which the thickness of the Naco beds involved in this between the Carboniferous fauna of Bisbee and that common characteristic forms (see illustration sheet close examination often shows to be made up very structure. Probably it is fairly safe to conclude of western Texas is particularly interesting in view 2) are the brachiopods Atrypa reticularis, Spirifer largely of fragments of crinoid stems. Near the that the original thickness of the Naco limestone of the fact that the Cambrian faunas of the two hungerfordi, and Schizophoria striatula, and the base the beds are commonly 10 to 15 feet in thick­ was more than 3000 feet. regions show a similar affinity. More than this, corals Pachyphyllum woodmani, Acervularia david- ness, but above the first hundred feet thicknesses of Lithology. The Naco limestone, like the Esca­ it will be shown later that the Cretaceous fauna of soni, and Cladopora prolifica. 1 to 5 feet are the rule, with occasional occurrences brosa formation, is made up chiefly of light-colored the Bisbee group finds its nearest analogue in por­ of more massive strata. The formation as a whole beds which consist essentially of calcium carbonate. tions of the Comanche series as developed in Texas. CARBONIFEROUS SYSTEM. may be characterized as a pure nonmagnesian lime­ The beds range in thickness from a few inches to RESUME OF THE PALEOZOIC SECTION. ESCABROSA LIMESTONE. stone, containing practically no arenaceous sedi­ 10 feet, but are usually thinner than those of the Name. The Escabrosa limestone takes its name ments and only occasional irregular bunches and Escabrosa limestone. They differ from the latter From the preceding descriptions it appears that from Escabrosa Ridge, where the thick white beds nodules of chert, usually in its upper part. also in texture, the typical Naco limestone being Paleozoic time is represented in the Bisbee quad­ belonging to this formation are conspicuous. Fossils are distributed through the formation, compact and nearly aphanitic, ringing under the rangle by beds having a total thickness of a little Distribution and general stratigraphy. The dis­ from the bottom to the top, but, with the exception hammer, and breaking with a splintery fracture, over 5000 feet. Of these, the lower 430 feet are tribution of the Escabrosa limestone is practically of small scattered corals and the abundant frag­ whereas the Escabrosa limestone is usually more quartzites, while the remaining 4570 feet are so that of the Martin limestone which underlies it. ments of crinoid stems, are rarely conspicuous and granular and crystalline and crumbles more readily predominantly calcareous that they may be col­ But its lighter hue, thicker beds, and greater power seldom appear on weathered surfaces of the lime­ when struck. There are, however, exceptions to lectively designated limestones. The Pennsylva­ of resisting erosion makes it a much more marked stone. As a rule they must be carefully sought this rule, dense aphanitic beds occurring rarely in nian is represented by at least 3000 feet of strata feature in the landscape than any of the limestones for, with a liberal use of the hammer. The gen­ the Escabrosa formation and granular crinoidal (the Naco limestone), while only 340 feet (the yet described. The summit of Mount Martin, the eral appearance of the Escabrosa formation is beds being not uncommon in the Naco limestone. Martin limestone) can be assigned to the Devonian. prominent light-colored scarps visible from Bisbee nearly white or light-gray, but some dark-gray Fossils, particularly brachiopods, are much more The Ordovician and the Silurian are wholly without along the northeast side of Escabrosa Ridge, and beds occur, particularly near the top. abundant in the Naco than in the Escabrosa lime­ stratigraphic representation, unless the unfossilifer- the bold cliffs which the same ridge presents toward stone, sometimes making up a considerable part of ous quartzite at the top of the Abrigo limestone Espinal Plain and Naco on the south are all due JiTACO LIMESTONE. individual beds, and weathering out conspicuously belongs in one of these periods. No unconformity to this formation. Name. The name Naco limestone is derived on exposed surfaces. has been discovered' to account for the absence of The most northern occurrence of the Escabrosa from the Naco Hills, situated near the western edge While the greater part of the 3000 feet or more recognizable Ordovician and Silurian strata, but limestone is a small area 5 miles west-northwest of of the quadrangle, and composed of the moderately of the Naco formation is made up of fairly pure unless the quartzite mentioned is of such age and Bisbee, on the edge of the quadrangle, resting thick, nearly white beds belonging to this forma­ gray limestone, certain thin beds of a faint pink represents the whole of the time, the region was with apparent conformity and gentle westerly dip tion. tint occur at several horizons and are often a use­ probably a land area during at least a part of the upon the Martin formation. Other areas north of Distribution and general stratigraphy. The ful means of distinguishing the Naco from the interval between the Cambrian and the Devonian. Moore Canyon extend the distribution of the beds Naco Hills, surrounded on three sides by the Escabrosa limestone. These pink beds, which, The typical white crinoidal limestone of the in a series of fault blocks westward beyond the Quaternary wash of Espinal Plain and San Pedro on weathering, usually show an inherent lamel­ Escabrosa formation is very nearly pure, contain­ bounds of the quadrangle, to the edge of the San Valley and cut off from the older Paleozoic rocks lar or shaly structure, are very fine grained and ing over 99 per cent of calcium carbonate. The Pedro Valley. Between Moore and Abrigo can­ on the north by the Abrigo fault, are carved from compact in texture. They effervesce freely with Naco, Martin, and Abrigo limestones are success­ yons the Escabrosa limestone has been removed by the Naco limestone, and their steep southwest cold dilute acid and are evidently composed ively more siliceous and contain more alumina and erosion. Nearly the whole thickness of the forma­ slopes afford exceptional opportunity for studying chiefly of calcium carbonate. Examination of iron oxides; but they consist essentially of calcium tion, however, is preserved on Mount Martin, and the lithological character of this formation. v The natural surfaces with a lens, however, shows the carbonate and the latter two are less impure than several faulted blocks of these beds occur south­ broader stratigraphic relations of the beds are, presence of minute quartz grains and tiny flakes of might be expected from their color and appearance. west and south of this peak, within a radius of 2|- however, not revealed in this relatively large but mica. Typical exposures of these pink calcareous Although the Abrigo limestone locally exhibits iniles. isolated exposure, where the only visible relation shales may be seen on top of Queen Hill, along dolomitic phases, it, like the other Paleozoic lime­ The Escabrosa limestones is also exposed in with .the other Paleozoic rocks is that of faulting. the trail connecting the Lowell mine with the No. stones of the quadrangle, is in the main practically Hendricks Gulch, just southwest of Bisbee1, and, Between the Naco Hills and Bisbee are several 2 shaft of the Lake Superior and Pittsburg mine, free from magnesia. like the Martin limestone, extends in a curved belt, smaller blocks of the Naco limestone, involved in and in the Naco Hills a mile northeast of Naco Mesozoic Sedimentary Rocks. broken by many faults, southeastward past Gold the intricate web of faults that characterizes the Junction. Hill as far as Glance Creek. v structure of this portion of the quadrangle, partic­ Chert is not uncommon in the Naco formation, GENERAL STATEMENT. The formation appears in most places to lie con­ ularly in the vicinity of Escacado Canyon. occurring sometimes as irregular bunches and The Mesozoic era is represented in the Bisbee formably above the Martin limestone, but the The largest area of Naco limestone within the nodules in beds of otherwise pure limestone, and quadrangle by a thick accumulation of conglomer­ contact is not always well exposed and has in some quadrangle, and by far the most important from an sometimes as the result of silicification of thin fos- ate, sandstone, shale, and limestone, which has been places been modified by faulting. This faulting, economic standpoint, is that which stretches south­ siliferous beds throughout their thickness. It is named the Bisbee group and is of Cretaceous age. chiefly along plains forming small angles with the eastward from Bisbee to Gold Gulch and is thence particularly abundant along and near zones of fis- It is probable that Triassic and Jurassic strata are bedding, is a particularly noticeable feature in the continued by a series of smaller exposures extend­ suring and faulting. absent. 5

CRETACEOUS SYSTEM (BISBEE that in the vicinity of Black Gap at the present characterize the formation as a whole, although its conglomerates sometimes alternate with 'beds of day. North of the gap the conglomerate occupies identification seldom presents any difficulty. The schist conglomerate like those north of Black Gap. NOMENCLATURE AND SUBDIVISIONS. an irregular basin. It probably attains a local most constant features are fairly distinct bedding, The calcareous pebbles of this area of the con­ Iii 1902 Durable described, under the name thickness of nearly 300 feet in the deepest part of imperfect rounding of the pebbles, considerable glomerate have been derived mainly from the Bisbee beds, an assemblage of arenaceous and cal­ this depression, and must formerly have been con­ induration, and a prevalent reddish color, particu­ Carboniferous limestones, particularly the Naco careous strata near Bisbee, assigning to them a siderably thicker. Hills of Paleozoic limestone larly of the matrix. The other and more variable limestone, which is known to underlie a portion thickness of about 3000 feet, and referring them project through the conglomerate at several points, lithological characters may best be exhibited by of the beds. The schist fragments were undoubt­ on satisfactory paleontological evidence to the Cre­ notably a mile northeast of Black Gap, where there describing actual occurrences of the conglomerate edly supplied by the Pinal schist, but whether they taceous. In this folio Dumble's name has been is excellent opportunity for studying the relation and noting the changes that appear as the forma­ came from the known areas north of Mule Gulch retained for the Bisbee group, which has been of the Glance formation to the irregular pre- tion is followed across the quadrangle from its or from ancient exposures in the southern part of divided into four formations. The lowest of these, Cretaceous surface upon which it lies (see fig. 9). northern to its southern border. the quadrangle now concealed by Cretaceous or the Glance conglomerate, derives its name from A similar conglomerate-filled depression forms the At the northern edge of the quadrangle the Quaternary deposits is not known. Similar uncer­ Glance, a station on the El Paso and Southwestern head of Gold Gulch, the conglomerate in all prob­ Glance conglomerate rests upon granite and is tainty obtains in regard to the pebbles of quartzite Railroad, near the Glance mine. The overlying ability attaining here a local thickness of over 200 composed of rather angular fragments of this rock and granite-porphyry. The Bolsa quartzite and Morita formation, chiefly sandstones and shales, is feet. mingled with bits of vein quartz. On Juniper the granite-porphyry intrusions of the northern named from the Morita Hills, lying just south of This contrast between the pre-Cretaceous topog­ Flat fragments of schist begin to be very abundant, half of the quadrangle could supply such mate­ the international boundary, between longitudes raphy north and south of Mule Gulch is a very and on the east side of Soto Canyon they make up rials, but it is not known whether the masses of 109° 45' and 109° 50'. %rhe Mural limestone, striking feature, the origin of which will be dis­ by far the greater part of the conglomerate. With these rocks now exposed were the actual sources overlying the Morita formation, is so called from cussed in the section devoted to the geological them, however, are associated occasional pebbles of of the conglomeratic material in the southern part Mural Hill, east of Bisbee. The topmost mem­ history of the quadrangle. granite, granite-porphyry, limestone, dark chert, of the quadrangle. ber of the group, the Cintura formation, composed Northwest of Gold Hill the conglomerate dips and vein quartz. At the head of Brewery Gulch, The small area of Glance conglomerate northeast of alternating sandstones and shales, derives its generally to the east or northeast at angles ranging just north of Bisbee, the Glance formation comprises of Glance station is composed almost exclusively name from Cintura Hill, near the northern edge of from 10 to 20 degrees. At Gold Hill, however, several rather irregular beds of dark red-brown con­ of rather coarse fragments of Carboniferous lime­ the quadrangle. The local upper limit of the Cin­ the beds are overridden by an overthrust block of glomerate containing lenses of red sandstone and stone, sometimes containing fossils. These imper­ tura formation and of the Bisbee group is a surface Paleozoic limestones and are locally turned up to a shale. Imperfectly rounded pebbles of schist pre­ fectly rounded pebbles are firmly embedded in a of Quaternary erosion. The definition of the group nearly vertical position in a compressed and slightly ponderate. These are occasionally as much as 8 compact, reddish, calcareous matrix of the same is therefore left somewhat elastic as concerns its overturned anticline. inches in diameter, but are usually smaller, the character as that cementing the conglomerates upper part, in the hope that future work in south­ About 1^ miles southeast of Gold Hill, the belt average being perhaps 2 or 3 inches. They are between Gold Hill and the Glance mine. eastern Arizona will discover the relation of the of conglomerate thus far described is cut off by a embedded in a dark-red sandy matrix, evidently Bisbee group to possible stratigraphic representa­ fault. derived from the disintegration of Pinal schist. MORITA FORMATION. tives of upper Cretaceous or Tertiary time. The area of Glance conglomerate stretching south­ The coarser material predominates in the lower Distribution, thickness, and general stratigraphy. Beds belonging to this group are known to enter ward from Gold Hill into Mexico presents by far part of the formation, while the increasing propor­ The Morita formation, consisting chiefly of alterna­ largely into the structure of the Mule Mountains the most extensive exposure of this formation within tion of sandstone and shale in the upper part pro­ ting beds of reddish shale and tawny sandstone, is north of the area here studied; they have been the quadrangle. Like the areas at. the head of Gold duces the effect of a partial transition into the over­ exposed within the Bisbee quadrangle in two main noted in great thickness by Dumble south of Gulch and north of Black Gap, it probably rests lying Morita formation. areas one an irregular belt traversing the quad­ Rucker Pass in the Chiricahua Range; and they upon an unevenly eroded surface of Paleozoic lime­ The conglomerate forming the area north of rangle almost diagonally from its northern edge to very probably occur in the San Jose Mountains stones, which in turn form part of the great fault Black Gap and at the head of Gold Gulch is gen­ its southeast corner, the other a much shorter, southwest of Naco. The sequence and thickness block that has been thrust bodily northeastward erally of a dull dark-red color and is made up prin­ parallel strip lying west of Gold Gulch and under­ of the various formations making up the group as over the belt of Glance conglomerate and Morita cipally of schist fragments, as may be well seen lying Armstrong's ranch, 5 miles east of Naco. it occurs in the Bisbee quadrangle are graphically formation lying on the northeast side of the dislo­ along the various roads running south from Bisbee In the former and larger area the beds dip gen­ shown in the accompanying generalized columnar cation. Toward the southwest, near Johnson's and in the excellent exposures on the divide a mile erally east-northeast in the northern part of the section. and Armstrong's ranches, the conglomerate passes northwest of Gold Hill. At the latter locality quadrangle, at angles ranging from 15 to 20 with southwesterly dip beneath the conformably were observed several slightly waterworn blocks of GENERAL DISTRIBUTION. degrees. The strata, however, are not merely overlying Martin formation. On the northeast the the schist which were fully 18 inches across, and a tilted, but frequently exhibit slight undulatory The rocks of the Bisbee group outcrop in a contact between the conglomerate and the Paleozoic few which measured 3 feet in diameter. As the folds with northeast-southwest axes. In the neigh­ broad belt, of general northwest-southeast trend, limestones is seldom exposed. In some places there rock underlying this mass of conglomerate is the borhood of Mule Gulch the strike of the beds occupying much of the northeastern and eastern appears to have been faulting between the Creta­ Naco limestone, the schist fragments which com­ becomes nearly northwest and southeast. The portion of the quadrangle. From Juniper Flat ceous and older rocks, while elsewhere the con­ pose the bulk of the material must have been dip is generally to the northeast, but varies from to Gold Hill this belt is bounded on the southwest glomerate apparently lies undisturbed upon the derived from areas of Pinal schist lying imme­ about 15 degrees in the lower beds near the by the sinuous line defining the unconformable slopes against which it was originally deposited. diately to the north and east, and now largely Glance conglomerate to about 60 degrees in the contact of the Glance conglomerate with the pre- The thickness of the conglomerate is undoubtedly buried beneath the Cretaceous beds. Not all of higher beds close to the Mural limestone. Cretaceous rocks, while on the east the beds pass much greater in this area than elsewhere in the the conglomerate, however, is of schist derivation, The hills between Gold Hill and Easter Sunday unconformably beneath the Quaternary detritus quadrangle. At the Glance mine a shaft was sunk for wherever hills of limestone protrude through mine are carved from the Morita formation. Near covering the floor of Sulphur Spring Valley. 500 feet before reaching the bottom of the con­ the Glance formation and along the southwestern the Gold Hill overthrust the beds are upturned South of Gold Hill the Bisbee sediments are glomerate, and as the same rock with gentle east­ border of the basin the lower part of the deposit is until they are practically vertical.' But the normal divided by over thrust faults into separate blocks, erly dip forms a hill just west of the mine that composed of blocks of limestone firmly cemented dip of 20 to 25 degrees to the northeast prevails which together form a belt about 6 miles in width, rises 400 feet above the collar of the shaft, the total with the usual reddish matrix. These angular along the main ridge and continues to within a short bounded on the east, west, and in good part on thickness of the formation is probably at least 600 fragments and imperfectly rounded limestone peb­ distance of the Easter Sunday mine, where the the south by Quaternary deposits. feet. As a whole the conglomerate beds of this bles were evidently derived from the immediately angle of dip again increases until an inclination of area form a gently flexed anticline (see the struc­ underlying Naco limestone. They lay upon the 55 degrees is attained near the base of the Mural GLANCE CONGLOMERATE. ture sections) having a nearly northwest-southeast limestone hill slopes, or formed talus heaps against limestone. Distribution, thickness, and general stratigraphy. axis. The two narrow exposures of Naco lime­ small cliffs, as may be seen a mile northeast of At about the line of this section the strike of The basal member of the Bisbee group is well exposed stone between Johnson's ranch and the Glance Black Gap, and after slight reworking by the the beds again swings into a nearly NNW.-SSE. just north of Bisbee as a distinctly bedded, red-brown mine are plainly old eroded ridges forming part of waves of the Cretaceous sea were buried beneath direction, which is retained to the southern edge conglomerate, from 50 to 75 feet in total thickness, the surface upon which the conglomerate was laid the abundant schist detritus that was carried into of the quadrangle. Northeasterly dips of from 20 resting upon a pre-Cretaceous surface of erosion down, and now exposed by erosion along the crest the basin from the north and east. to 35 degrees prevail in this portion of the area, carved upon the Pinal schist. This old surface is, of the low post-Cretaceous anticline. The belt of conglomerate which passes from the except along its southwest border, where the beds in this part of the quadrangle, a nearly even plain Near the overthrust fault which is defined topo­ head of Gold Gulch through the saddle northeast are locally disturbed in the vicinuVy of the Gold that has been tilted about 15 degrees to the east, graphically by the open valley between Glance of Gold Hill and thence eastward toward Black Hill overthrust fault. and which, as it emerges from beneath the Glance station and Christianson's ranch the beds of con­ Knob contains some beds of grit and shale asso­ The beds of the second area of the Morita forma­ conglomerate, is recognizable as a well-marked glomerate have a local southwest dip and are in ciated with the usual coarser conglomerate. The tion that surrounding Armstrong's ranch have topographic bench formed by the tops of the schist places nearly vertical. They thus form a narrow pebbles of the latter are principally schist and the same general strike as those between the ridges north of Bisbee and by the gently inclined syncline along the northeast border of the main granite (or granite-porphyry) with some limestone. Glance mine and Christianson's ranch. Their dip, surface of Juniper Flat (see fig. 10). The con­ anticline. The low hills stretching southward from. Gold however, is southwesterly at an angle of about 15 glomerate continues northwestward, retaining a ,The only other area of Glance conglomerate that Hill to the international boundary are carved from degrees. They conformably overlie the Glance fairly constant thickness, to within a mile of the requires particular mention is a small one (super­ conglomerate similar in general appearance to that conglomerate of Gold Gulch and underlie the northern edge of the quadrangle, where it thins ficially divided in two by a strip of Quaternary north of Black Gap. Pebbles of schist, quartzite, Mural limestone of the low hills 4 miles east of out rather suddenly and for a distance of about material) occurring about a mile northeast of granite, granite-porphyry, and vein quartz were Naco. Were it not for the complication intro­ 1500 feet is wanting, the Morita formation resting Glance station, on the edge of Sulphur Spring noted, and the fragments of schist in particular duced by the Gold Hill overthrust, they might be directly upon the granite. The conglomerate Valley. This, also, lies upon the back of an over- sometimes make up a considerable part of the considered simply as the southwestern limb of a comes in a,gain, however, toward the north' and thrust block of Paleozoic (Naco) limestone, which upper beds, as in the vicinity of Johnson's ranch low anticline of which the beds southeast of Glance continues beyond the bounds of the quadrangle. has been shoved, in this case from the east, over and in the lower part of Gold Gulch. form the northeastern limb. Toward the southeast the conglomerate, interrupted the Cretaceous (Mural) limestone. But near the Glance mine and along the line of The thickness of the Morita formation as meas­ by some faulting and becoming rather thinner, Lithology. The pebbles and fragments that the El Paso and Southwestern Railroad the forma­ ured in the excellent exposures north and east of extends to Mule Gulch, where it is offset to the make up the Glance conglomerate have been tion is composed mainly of beds made up almost Bisbee is 1800 feet. west by a series of post-Cretaceous faults. derived from the pre-Cretaceous rocks of the exclusively of pebbles of limestone embedded in a Lithology. The Morita formation comprises South of Mule Gulch a marked change occurs in region and have, as a rule, undergone no consider­ reddish matrix which effervesces freely with acids uniformly alternating beds of dull-red shales and the formation. Instead of resting as a smoothly able transportation. To a certain extent, therefore, and is evidently also composed of detritus derived red or tawny sandstones, with occasional layers of spread and rather thin deposit upon a nearly plane the distribution of the derivative materials of the chiefly from limestones. Good exposures of these grit and lenses of impure limestone. Although surface, the Glance conglomerate becomes exceed­ conglomerate corresponds with the areal disposition limestone conglomerates are found in the railroad some of the strata are 10 or 15 feet in thickness, ingly variable in thickness and fills the hollows in of the underlying rocks which supplied the con­ cuts and along the sand-scoured rocky bed of the formation as a whole is characterized by beds a buried topography scarcely less diversified than glomeratic detritus. It is thus rather difficult to Glance Creek. It can be seen that these limestone ^f moderate thickness, usually less than 4 feet. Bisbee. 6

The general landscape tints are dull red or yellow­ ready disintegration of some thin, impure limestone The upper member of the Mural formation, follow from 100 to 150 feet of red shales, thin- ish brown, dependent upon the local predominance in its lower part. unlike the lower beds' just described, outcrops bedded sandstones, and arenaceous gray or green­ of the red or tawny beds. As a rule the red color If local concealment by Quaternary deposits and prominently, usually forming a cliff. The strata ish limestones. Some of the limestones contain prevails near the base and the yellow tones in the some irregularities due to faulting be disregarded, range from gray to white, and thus contrast strik­ fossils, particularly a Turritella, which is appar­ upper pail of the formation. it may be said that the Mural limestone is exposed ingly with the sober red and tawny tints of most ently identical with the form so abundant in The red shales are finely arenaceous and not in a relatively narrow belt which, entering the of the sediments composing the Bisbee group. At the lower member of the Mural limestone. Upon particularly fissile. In fact, when they have not quadrangle at about the middle point of its north­ the bottom, resting upon the buff sandstone at the these transitional beds repose red nodular shales been exposed to the weather they are tough, ern boundary, pursues a southerly course until it top of the lower member, are two or three beds of with occasional strata of buff sandstone and very compact rocks with no distinct cleavage. The reaches the latitude of Bisbee; thence it sweeps hard gray limestone which constitute practically subordinate beds or lenses of impure, greenish, nod­ cementing material is calcite, as shown by the free southeastward to the edge of Sulphur Spring a single massive stratum from 40 to 60 feet in ular limestone, the whole having a thickness of from effervesence of the shale in dilute acid. Little, Valley, and, again curving southward, maintains thickness. This is the cliff-making portion of the 700 to 800 feet. The individual sandstone beds light-gray, concretionary, calcareous nodules are a a south-southeast course until it passes out of the Mural limestone. Above it lie beds of similar sometimes attain a thickness of 6 feet, but are characteristic feature of the red shale. They are southeast corner of the quadrangle into Mexico. lithological character but distinctly thinner, rang­ greatly surpassed in volume by the shales. Over­ particularly conspicuous on weathered surfaces and On the north the Mural limestone, like the beds ing usually from 6 to 10 feet in thickness. lying these dominantly shaly beds are 300 feet of might readily be mistaken at first glance for peb­ of the Morita formation, dips generally to the The gray limestones are richly provided with flaggy, cross-bedded, gray and buff sandstones with bles of limestone. In the upper part of the for­ northeast at angles ranging from 10 to 20 degrees. fossils, but these do not weather out readily, and occasional parting layers of red shale. These mation the red shales become still more calcareous. The breadth of the outcrop in the vicinity of Dixie the tough, compact nature of the matrix renders sandstones usually form a rough cliff or scarp along The gray nodular concretions increase in abun­ Canyon is due to this low angle of dip, to the their collection difficult. One or more species of the hill slopes overlooking Mexican Canyon. They dance, and occasional thin beds or lenses of com­ presence of some shallow folds with northwest- Ostrea, in individuals up to 7 inches in length, are are succeeded in turn by about 600 feet of reddish pact gray limestone appear within the shales, into southeast axes, and to minor faulting. At the abundant, particularly in the very thick beds at nodular shales interbedded with flaggy cross-bedded which they grade above and below. As a rule point where the beds turn southeast toward Mule the base of this upper member, while in the higher sandstones. One of the latter beds, about 18 the limestone lenses are not fossiliferous, although Gulch the dip becomes steeper, and where the beds the little disk-like Orbitolina texana is very inches in thickness, occurring about 1600 feet in some of the sections exposed northeast of Bisbee limestones are crossed by the road to Forrest's common and is associated with the so-called above the base of the Cintura formation (or about and in the little hills southwest of Armstrong's ranch they attain a maximum dip of 65 degrees to Carjrina occidentals, the large gasteropod Lunatia 200 feet below the present top), has a pale-cream ranch they contain molluscan fossils of the same the northeast. Southeast of the Easter Sunday pedernalis, and a coral of the genus Astroccenia. tint and by contact with the darker hue of the rest types as those occurring near the base of the over­ mine the dip decreases until it is from 20 to 30 Casts were seen which suggested the occurrence of of the formation is conspicuous as a light band lying Mural limestone. degrees. The unusually steep dip of the Mural a large Ueqidenia, but no distinct shells of this near some of the hilltops east of Grassy Hill. The sandstones alternating with the shales fre­ limestone near Mule Gulch is associated with dips genus were found. Part of a well-preserved quently show cross-bedding, and range in color nearly as great in the adjacent Morita and Cintura ammonite in the possession of Mr. W. G. McBride AGE OF BISBEE GROUP. from reddish brown to buff or tawny. They are beds. The inclination of these beds rapidly dimin­ of Bisbee, said to have been picked up in Brewery The various collections of fossils made during usually fairly hard, fine-grained rocks in which the ishes, however, both to the northeast and to the Gulch, suggests that this form also may occur in the progress of the field work, chiefly from the original sand grains have been cemented by calcite. southwest, away from the Mural limestone, the lat­ some portion of the Mural limestone exposed at Mural limestone, were submitted to Dr. T. W. In the upper part of the formation, however, are ter exhibiting the maximum effect of this local the head of that gulch. Stanton, who reports that the fossiliferous horizon occasionally hard tawny to buff-colored beds in upturning of the strata. The little hills near the eastern edge of the represented corresponds in large part with the Glen which the cementing material is quartz. These A mile northeast of Glance station the Mural quadrangle north of Hay Flat are composed Rose beds of Texas and that possibly the upper might, therefore, properly be called quartzite. limestone is partly covered by a fault block of mainly of the hard limestones of the upper mem­ portion is as high as the Edwards limestone; in Microscopical examination of a representative Naco limestone that has been thrust over it from ber of the formation. Some of the beds here con­ other words, that they certainly belong to the specimen of the sandstone shows it to consist of the east. tain abundant corals (Astroccenia and another form Trinity division, and possibly in part to the Fred- incompletely rounded grains of quartz, frequently In addition to the principal area just described, not collected), "Caprina," and a number of little ericksburg division of the Comanche series. showing crystal enlargement by the growth of new the quadrangle contains several smaller exposures brachiopods (Rhynchonella, Terebratella, and Tere- Mr. Stanton's report definitely assigns the Mural quartz upon the worn particles, and a few frag­ of the Mural limestone. Such are the small hills bratula) not seen at any other locality in the quad­ limestone to the lower Cretaceous or Comanche ments of plagioclase. The interstices between the rising out of the Quaternary deposits near the east­ rangle. epoch. Direct paleontological evidence for as detrital grains are filled with crystalline calcite. ern edge of the quadrangle, opposite the mouth of As a rule, the upper member of the Mural for­ satisfactory a determination . of the three other About 1200 feet above the base of the Morita Glance Canyon. The beds forming these hills dip mation, consisting almost if not quite exclusively members of the Bisbee group is not obtainable. formation occurs a bed of reddish-brown grit from to the southwest and constitute the western limb of of gray limestone, is conformably overlain by a The conformable sequence of the beds, however, 10 to 15 feet in thickness, but otherwise there is no an anticline, the other limb being partly represented bed of rather vitreous buff quartzite. The contact considered in connection with the lithological marked interruption in the monotonous repetition by similar hills projecting above the Quaternary between these two rocks has been chosen as the transitions between the various stratigraphic units, of sandstones and shales extending from the top of deposits farther east. Another small area is that boundary between the Mural limestone and the and the practical identity in character of the Morita the Glance conglomerate to the bottom of the near boundary monument 91, 4 miles east of Cintura formation. But as in the cases of the and Cintura formations, below and above the fos­ Mural limestone. Naco. The strata here conformably overlie the Mural limestone and the Morita formation, the siliferous Mural limestone, leave no room for any Between the Morita formation and the Mural Morita beds of the Armstrong's ranch area and dip division so made is somewhat arbitrary. Lime­ reasonable doubt of the Comanche age of the whole limestone, next to be described, there exists no to the southwest. They continue southeastward stone strata from 3 to 5 feet in thickness continue Bisbee group. sharp natural boundary. The doininantly arena­ into Mexico. The last' area to which attention to occur in alternation with sandstones and shales ceous Morita beds pass upward through transi­ need be particularly directed lies a little less than throughout the lower 100 to 150 feet of the Cin­ Quaternary Deposits. tional phases into the dominantly calcareous Mural a mile southeast of Gold Hill. It is a small block, tura formation, and occasionally contain Turritella Distribution. Deposits referable to the Quater­ limestone. The divisional plane chosen for descrip­ bounded by faults. The interesting questions pre­ and other fossils that are apparently identical with nary period cover fully half of the Bisbee quad­ tive purposes is that defined by the upper surface sented by the occurrence of a little isolated mass of forms occurring in the Mural limestone. rangle. They are not deeply channeled, and of a bed of hard buff sandstone or quartzite, which, Mural limestone at this place will be considered in natural sections of any but the superficial portiojis CINTURA FORMATION, as may be seen from the geological map, outcrops the section devoted to geological structure. of the material do not occur. :» , below the Mural limestone to the east of Bisbee in Lithology. -Although mapped as a unit, the Distribution, thickness, and general stratigraphy. The Quaternary deposits occupy the main floors fuch a manner as to find topographic expression Mural limestone, with a thickness of 650 feet, is The occurrence of the sandstones and shales of the and embayrnents of the larger valleys, such as in a series of little bench-like spurs, easily recog­ readily divisible into at least two stratigraphic Cintura formation within the Bisbee quadrangle is Sulphur Spring Valley and Espinal Plain, and nized by anyone looking along the general line of .members a lower portion, about 300 feet in limited to a single area, which lies along the edge rise in gentle slopes toward the Mule Mountains. contact of the two formations. Immediately over­ thickness, comprising thin-bedded impure lime­ of Sulphur Spring Valley and extends northward Against these they terminate in a very irregular lying this sandstone is a bed of dark, impure lime­ stones, and an upper portion, 350 feet thick, in from the vicinity of Forrest's ranch past Cintura line, which is nearly everywhere rather indefinite stone made up in considerable part of broken which relatively thick-bedded and pure limestones Hill and beyond the northern boundary of the owing to the insensible passage of the slightly shells, chiefly Ostrea. The divisional plane marks predominate., The lower member is represented quadrangle. The beds form a generally very shal­ transported materials of the valley deposit into the practically the upper limit of the sandstones and topographically by the smooth under-cliff slope. low syncline which pitches northeastward under loose, stony detritus that cumbers the hill slopes. red shales, although it does not absolutely define Its exposures are seldom conspicuous and show the Quaternary deposits of Sulphur Spring Val­ Along the eastern front of the mountains the the lowest appearance of fossiliferous limestones. subdued greenish-yellow, dark-green, brownish, or ley, at an angle of about 20 degrees. Near Mule Quaternary of Sulphur Spring Valley buries the gray tints. The top beds of the lower member are Gulch, along the contact with the Mural limestone, slopes of the older rocks up to an average altitude MURAL LIMESTONE. usually buff sandstones, which may have a total the Cintura strata at the rim of the generally of about 4600 feet. The boundary between the Distribution, thickness, and general stratigraphy. thickness of 25 feet. Below these are rather soft, slightly^ hollowed syncline are locally upturned Quaternary of Espinal Plain and the southern As one approaches Bisbee through the southern thin beds of sandy limestone, sometimes grading until they attain a dip of 50 degrees, which, how­ front of the Mule Mountains attains a greater ele­ passes, particularly when the noonday glare has into cross-bedded, highly calcareous sandstone, with ever, rapidly dijnlnlsh.es toward the north. ) vation but is so irregular as to render a general softened into the shadows of \evening and the occasional thicker beds of dark-gray shell lime­ The total thickness of the beds belonging to the description difficult. Its average elevation may beauty of the sculptured hills is compensation for stone, composed almost entirely of oyster shells Cintura formation exposed in this syncline is at be roughly given, however, as about 5250 feet, their barrenness, he is confronted by a prominent (Ostrea}. Molluscan remains are plentiful in cer­ least 1800 feet. The original thickness of the although in Escacado Canyon, northwest of Don light-gray cliff crowning Mural Hill and stretch­ tain of these beds, although not always well pre­ formation is unknown, its present upper limit Luis, characteristic Quaternary deposits extend to ing like a rampart along" the face of the ridge served. The genera most commonly represented being an irregular surface determined by Quater­ an elevation of 5650 feet. northeast of town. This cliff, giving scenic dis­ are Ostrea, Turritella, Lunatia, Cyprina, Trigonia, nary erosion. Lithology. Near the mountains the Quaternary tinction to otherwise rather commonplace hills, is and in one highly fossiliferous bed exposed just - Lithology. In general lithological character the deposits consist, as a rule, of rather coarse and formed by a portion of the Mural limestone (see northeast of monument 91, on the international Cintura formation is a repetition of the Morita imperfectly rounded stony detritus which has evi­ fig. 1). Below the cliff, which varies from 50 to boundary, well-preserved individuals of Pecten formation. It is characterized by the same reddish, dently beSn^derived from the adjacent slopes and 250 feet in height, is a smooth, steep slope, about stanioni are abundant. Exceptionally favorable sometimes almost purplish shales, with gray ^nodu­ rarely exhibits distinct bedding. Along the west­ 200 feet from top to bottom, and at the foot of localities for making collections of representative lar concretions, the same occasional bands of gray ern edge of Sulphur Spring Valley the fragments this slope a line of projecting spurs marking the fossils of the Bisbee group are found in the nearly limestone, and the same tawny, buff or pinkish, have-been supplied chiefly from the harder sand­ outcrop of the topmost bed of the Morita formation. isolated and faulted area of Mural limestone 2J cross-bedded sandstones with quartzitic phases. stone Jbeds of the Bisbee group. Along the north­ The cliff and slope are genetically related and are miles northeast of Bisbee, on the slopes beneath The stratigraphic arrangement of the beds, how­ ern border of Espinal Plain fragments of Paleozoic the topographic expression of the resistance to the cliffs in the vicinity of Mural Hill, and on the ever, is different. Immediately overlying the limestone greatly preponderate over those of any erosion of certain thick, hard beds composing the northeast side of the little group of hills 4 miles Mural limestone there is usually a bed of buff other rock, and are often found to be superficially upper part of the Mural limestone, and of the east of Naco. quartzite from 10 to 15 feet in thickness. Then consolidated into hard conglomerate through the 7 addition of a white, travertine-like cement. Such Bisbee region is an expression of that fact rather IT. Alkali granite; Drammen, Norway. Rosenbuseh, Occurrence and distribution. Granite-porphyry Cfesteinslehre, 1898, p. 78. cemented material is frequently not unlike certain than of differential changes of level. III. Granite-porphyry; sill in Bolsa quartzite, 3J miles occurs chiefly in the northwestern part of the quad­ phases of the Glance conglomerate, but may be north of Naco Junction. George Steiger, analyst. rangle, in the form of dikes and irregular intrusive Igneous Rocks. distinguished by its white, travertine-like matrix, IV. Rhyolite (aporhyolite); probably volcanic neck, 2J masses cutting all of the formations from the Pinal miles northeast of Naco Junction. George Steiger, analyist. as contrasted with the reddish matrix of the older GENERAL STATEMENT. schist to the Naco limestone, and less commonly as rock. The maximum depth to which this cemen­ The eruptive or igneous rocks of the Bisbee The rock is shown by the analysis to belong small sills intercalated between the beds of Bolsa tation extends is unknown, but the local depth is quadrangle are for the most part intrusions of to the class known as alkali granites. quartzite. The rock is readily recognized by its certainly in many places very slight. Prospecting granitic magma, ranging in form from small dikes By calculation, the chemical analysis affords the usual pinkish or occasional buff tint, by its pits less than six feet in depth frequently pass and sills to stocks of considerable size, and in tex­ following: speckled appearance, due to the contrast of the por­ through the cemented crust into comparatively ture from rhyolite to granite. Per cent. phyritic crystals of quartz and feldspar with the soft and loose material. Quartz ...... 34.68 compact reddish groundmass, by its erratic occur­ In addition to these are a few small dikes of Orthoclase molecule...... 29.47 This calcareous matrix belongs to the class of monzonitic porphyry and occasional insignificant Albite molecule...... 30.39 rence within the limestones, quartzite, and schist, deposits known in Mexico and southern Arizona dikes of a decomposed greenish eruptive which was Anorthite molecule...... 2.50 and by its clearly intrusive character. Biotite, tourmaline, zircon, magnetite, etc.. 2.96 as caliche. probably originally diabase. Numerous small dikes of granite-porphyry occur Away from the mountains the Quaternary 100.00 within the pre-Cambrian schists between Bisbee deposits become finer and exhibit more or less GRANITE. Microscopical determinations indicate that the and Juniper Flat. For the most part these dikes irregular cross-bedded stratification. The well Definition. Granite is a wholly crystalline, sodium-calcium feldspar present in the rock is have no observable connection with the granite west of Naco from which water is pumped to Bis- granular, eruptive rock, consisting essentially of oligoclase having an approximate composition of 4 mass of Juniper Flat, One of them, however, bee by the Copper Queen Company is 118 feet orthoclase (or some other member of the group of molecules of albite to 1 of anorthite (Ab4 Ai^). cuts the latter a third of a mile southeast of Mule deep and is apparently wholly in Quaternary alkalic feldspars), quartz, and usually muscovite, The mineral composition of the granite may Pass and is accordingly younger than the granite. material. For a distance of 100 feet from the biotite, or amphibole, with small quantities of vari­ accordingly be given as: Similar dikes are found traversing the schists of surface this was so soft as to require timbering. ous accessory minerals, such as apatite, zircon, and Tombstone Canyon, on the southwest side of the Per cent. Apparently no record was kept of the exact nature magnetite or ilmenite. Chemically, the rock may Quartz...... 34.68 granite stock, particularly near Brown's, ranch in of the material passed through, but the dump contain from 70 to 78 per cent of silica, 11 to 16 Microperthitic orthoclase (Or9 Ab2)...... 41.00 the extreme northwest corner of the quadrangle. Oligoclase (Ab^AnJ ...... 21.36 shows that it was principally a partly consoli­ per cent of alumina, rarely more than 4 per cent Biotite, tourmaline, etc...... 2.96 While the relation of these dikes to the granite is dated reddish sand containing occasional small of the iron oxides, usually less than 1 per cent not always clearly shown, they are in some cases 100.00 pebbles. Similar soft sandy beds, containing of magnesia, seldom over 3 per cent of lime, and undoubtedly direct offshoots from the latter, as fragile fresh-water shells of the genus Unio, have commonly from 5 to 8 per cent of alkalies, the The coarser phase of the granite to which the may be well seen just north of Brown's ranch. been encountered in boring for a well at the new potash usually preponderating over the soda. foregoing description particularly applies is char­ It is on the southwestern slope of Escabrosa Copper Queen smelter near Douglas, in the mid­ Occurrence and distribution. The only granite acteristic of the western portion of the stock, in the Ridge, however, that the granite-porphyry dikes dle of the Sulphur Spring Valley. found within the quadrangle is that composing the vicinity of Cox's ranch. Finer grained varieties, attain their most interesting development. They According to Mr. W. M. Adamson, superintend­ elongated intrusive stock which cuts the Pinal however, also occur, particularly on Juniper Flat have a general northwest-southeast trend, and are ent of machinery at the reduction works, the mate­ schist in the vicinity of Tombstone Canyon, north­ and near the basal boundary of the Cretaceous most abundant within a belt about a mile wide rial encountered in this well was as follows: west of Bisbee. The rock is well exposed both at beds. The evidence obtainable in the field indi­ stretching northwestward from the vicinity of Record of noell at Douglas. Mule Pass and on Juniper Flat, and forms the cated that the difference between these fine-grained Don Luis to the western edge of the quadrangle. Feet. bold cliffs overlooking from the northeast the road facies and the coarsely crystalline type selected Within this zone the dikes, ranging in width from Surface loam ...... 15 a foot to half a mile, branch and cross, forming Sand and gravel, containing abundant shells in down Tombstone Canyon. Within the quadran­ for chemical analysis was textural only. Micro­ its upper part, and affording 120 gallons of gle, the stock has a length of about 5 miles and scopical study, however, shows that there is a min- an intrusive network of great complexity. Many water per minute...... 22 probably extends northwestward for an additional eralogical and chemical difference as well. The of the broader intrusions shown on the geological Very white calcareous clay...... 15 Compact red clay...... 75 mile or so beyond the northern boundary. Its fine-grained pink granite from the northern part map are so crowded with masses of schist, quartz­ Sand, affording about 3 gallons of water per width is at least 2 miles, but the northeastern con­ of Juniper Flat consists chiefly of quartz and ite, or limestone, as to be in reality complexes of minute ...... 1 many dikes, for which simplified representation Red clay...... 6 tact of the mass is partly concealed by overlapping orthoclase, with very little oligoclase, even less Very hard red clay...... 1 Cretaceous beds. biotite, and, as far as known, no tourmaline. is demanded by the scale of the map. Red clay with considerable grit...... 36 Petrography. The granite of Juniper Flat and The dominant minerals form an allotriomorphic As a rule the dikes occupy fault fractures, along Water-bearing sand and gravel...... 6 of the cliffs northeast of Tombstone Canyon has aggregate, with a tendency on the part of the many of which it is evident that there was con­ Total depth...... 177 a typical granitic texture, without any marked quartz to poikilitically inclose the orthoclase. In siderable displacement before the fissure was finally At the above depth, the well yielded 245 gallons peripheral or contact modifications. The average mineralogical composition and texture, therefore, sealed by the intrusion and solidification of the of water per minute, and as this was all that the diameter of the crystalline grains is about 7 milli­ the rock belongs with those aplitic granites for granite-porphyry magma, Such a dislocation is pump could handle, sinking was for the time dis­ meters. In color the rock is reddish-gray, with a which the name alaskite has been proposed. well shown about 2 miles south of Brown's ranch, continued. suggestion of pink when viewed in large masses. In chemical composition the fine-grained granite near the edge of the quadrangle, where the Esca­ A second well, started by the same company The minerals visible with the unaided eye are a just described corresponds more nearly than the brosa limestone on the northwest side of the main near the one just described, had reached a depth reddish-brown unstriated feldspar quartz, a white coarser variety analyzed to the granite-porphyries dike has been dropped 500 feet below the base of of about 400 feet in April, 1903. At the last feldspar shoAviiig distinct polysynthetic twinning next to be considered, in which a similar mineral­ the Bolsa quartzite on the northeast side of the report received this well was all in unconsolidated lamellae, and a very little black mica in small flakes. ogical association is also connected with a marked dike-filled fissure, indicating a throw of more than material. At 120 feet a good flow of water was The microscope shows that the brown feldspar is preponderance of the potash molecule over that of 2000 feet. Farther to the southeast the total tapped, and at 355 feet, the drill, after penetrating microperthitic orthoclase, crowded with the usual soda (see analysis I). Although there can be little throw has been distributed among the many a bed of compact clay, entered a thin layer of minute dusty inclusions. This mineral, with doubt of the essential unity of the Juniper Flat branches composing the dike zone, but the aggre­ water-bearing gravel. The water from this stratum quartz, a smaller amount of sodic oligoclase, and a granitic stock, and although additional analyses gate displacement must be nearly or quite as great. rose to within 3 feet of the surface. little biotite, forms an allotriomorphic aggregate would probably show close agreement as regards These fissures are not always occupied "by dikes Origin. The Quaternary deposits of the Bisbee making up the greater part of the rock. The silica, alumina, iron oxides, lime, magnesia, and for their whole lengths. It is ndt uncommon to quadrangle consist of the waste or "wash" shed accessory minerals are tourmaline, muscovite, total alkalies, yet the mass evidently exhibits con­ find a dike becoming narrower and finally disap­ from the Mule Mountains (and, near Naco, from apatite, zircon, and magnetite or ilmenite. Of siderable variation as regards the relative propor­ pearing while the fault fissure can still be readily the San Jose Mountains also) into the surrounding these, the tourmaline is of most interest. It occurs tions of potash and soda, and it is accordingly followed. An excellent example of this may be valleys. Although the beds are undergoing some in nests of small prisms, the latter being frequently unsafe to assume that the analysis given under seen near the head of Abrigo Canyon. local dissection, they belong essentially to the embedded in muscovite but penetrating also the I is -representative of the intrusion as a whole. Although some of the dikes on Escabrosa Ridge present cycle of topographic development and are quartz and orthoclase, showing that it is a primary There is good reason to suspect that the tourma­ are nearly vertical, most of them dip steeply to the the work of streams similar in their mode of activ­ constituent. The prisms show the characteristic line-bearing granite analyzed contains less potash northeast. Consequently the displacement along ity and in some cases nearly coincident in position strong absorption, rounded, trigonal cross sections, and more soda than the average rock of the stock. their fissures corresponds in the greater number of with those of the present day. No physical break and obtuse terminations characteristic of tourmaline. cases to reversed faulting. GRANITE-PORPHYRY. has been detected in this region between the early A chemical analysis of the granite is given below Occasionally, the dikes as they passed upward Quaternary (Pleistocene) and the late Quaternary under I, while an analysis of a similar granite from Definition. Granite-porphyry is a wholly crys­ from the Pinal schist into the Bolsa quartzite, (Recent) formations. Throughout the entire Norway is placed alongside under II, for compar­ talline eruptive rock having the same chemical and took advantage of the bedding planes of the latter Quaternary period the streams have been engaged, ison. mineralogical composition as granite but distin­ to expand in the form of irregular sills, as may be in sculpturing the mountains and distributing the guished from the latter by a porphyritic instead of seen in Bolsa Canyon and between Abrigo and detritus over the valleys as fluviatile deposits, Analyses of granites, granite-porphyry, and rhyolite. granular texture. That is, the quartz and feldspar Moore canyons. I. n. III. IV. which range from coarse, imperfectly rounded Si0 2 ...... 75.86 76.05 78.81 76.78 occur as sharply bounded crystals or phenocrysts That the dikes of Escabrosa Ridge were not all gravels near the mountain fronts to pebbly sands Al O ...... 12.17 11.68 10.96 embedded in a distinctly finer grained matrix or intruded at precisely the same time is proved by a and even finer silts near the valley axes. Fe2O 8 ...... ' .85 .34 1.18 groundmass. This groundmass may be, and in the few instances in which one dike clearly cuts others. FeO ...... 36 1.06" .08 There is no evidence indicating that any part of MgO...... 29 .14 Bisbee quadrangle usually is, aphanitic, or so fine Rhyolitic dikes have been observed cutting those the Bisbee quadrangle was covered by any consid­ CaO...... 62 .42 grained as to show no crystalline texture to the of the more abundant granite-porphyry type, while Naa O...... 3.60 3.79 .26 .30 unaided eye. in other cases the relation is reversed. erable body of standing water during Quaternary K8 0...... 5.04 5.09 8.50 9.28 time; but it seems highly probable that at least H 2 0...... 27 ) 1:86 .48 The granite-porphyries are divided by no defin­ Although many of the granite-porphyry dikes ex­ H 3O+ .... 72 \ 1.17 hibit no selvage modifications, others pass near their temporary lacustrine conditions prevailed in por­ TiD 21 .05 .13 ite line from the rhyolites, in some of which the tions of the broader valleys, such as San Pedro ZrO 2 ...... not det. .42 groundmass, prevented by rapid cooling from walls.into rhyolitic facies showing flow banding. or Sulphur Spring. The occurrence of fresh-water CO2 ...... assuming a wholly crystalline texture, solidified in One of the most important masses of granite- p o shells in the Quaternary deposits beneath Douglas F...... part as volcanic glass. Both of these textural porphyry, on account of its relation to the ore indicates the former presence there of a lake, or at s...... modifications of the granitic magma occur within bodies of the district, is that forming Sacramento MnO...... none the Bisbee quadrangle, but as they are of the same Hill, just southeast of Bisbee. This is a stock least of a perennial stream, neither of which could Li2 O ...... exist with the present scanty precipitation. It is general geological age and are derived from the which, although of irregular outline and partly 99.70 100.54 99.71 therefore probable that the Quaternary has been same magma, their separate mapping would serve concealed on the east by Cretaceous beds, may be I. Tourmaline-bearing alkali granite; intrusive stock in no useful purpose, and the rhyolite is accordingly described as about a mile in diameter. Like most marked by increasing aridity, and that such dis­ Pinal schist, 5 miles northwest of Bisbee, Arizona. George section of its deposits as has taken place in the Steiger, analyst. included with the predominant granite-porphyry. of the porphyry intrusions of the quadrangle, it is Bisbee. closely related to a fault, but instead of following By calculation the following conventional com­ weathered amygdaloidal lava. Rock of this char­ blages or groups, and these groups subdivided into the fissure as a narrow dike, the magma has invaded position is obtained from the chemical analysis: acter is abundant in the vicinity of the Gardner geological units. Finally the present distribution, the rocks on both sides of the fracture and formed shaft and on the ridge extending from that shaft form, and lithology of each unit have been Per cent. a rudely cylindrical, intrusive plug. On the north­ Quartz...... 42.78 toward the ice factory. described, and some conclusions reached as to age east this plug or stock cuts the Final schist; on the Orthoclase molecule...... 50.04 The crest of this ridge corresponds roughly with and origin. Albite molecule...... 2.10 southwest it cuts the Naco limestone and at greater Hematite, magnetite, water, etc...... 5.08 the outer limit of the notably metamorphosed All this, however, is preliminary. The rocks are zone as visible on the surface. The boundary merely the materials from which geological forces depths, in all probability, the Escabrosa and older 100.00 formations. between altered and unaltered limestone is, how­ have fashioned a complex structure that will require A much smaller plug-like mass occurs 2J- miles As no albite is visible in thin section under the ever, extremely irregular and often indefinite. further labor for its elucidation and comprehension. northeast of Naco Junction, forming a little conical microscope the albite molecule is probably com­ Certain beds retain nearly their original texture In the production of this rocky fabric, faulting, hill, which owing to its shape and to the contrast bined with the orthoclase molecule in the mineral and composition close up to the porphyry, while folding, and igneous intrusion have' cooperated, of its dark-brown color with the surrounding orthoclase. The rock thus consists of 42.78 per others are obviously altered for long distances often so intimately that it becomes impossible to limestones, is a conspicuous feature as seen from cent of quartz and 52.14 per cent of orthoclase, from the intrusive contact. consider the part played by any one of these Espinal Plain. The rock composing the upper with 1.65 per cent of water and 3.43 per cent of The Pinal schist in the vicinity of the porphyry dynamic processes without referring to the others. part of this hill is of much darker hue than the iron oxides, zircon, and indeterminate accessory of Sacramento Hill has lost its schistose structure The structure of the quadrangle, however, is pre­ usual granite-porphyry of the quadrangle and has minerals. and become a fine-granular aggregate of quartz and eminently characterized by faults, and to these a pronounced vertical fluidal structure trending The rock with conspicuous flow banding form­ sericite containing abundant disseminated pyrite. some preliminary attention will now be given. nearly north and south. It is more properly ing the little hill 2|- miles northeast of Naco Junc­ The porphyry itself exhibits throughout much Faults. classed as a rhyolite than a granite-porphyry. On tion shows in hand specimens minute phenocrysts of its mass a similar alteration, of which the DISTRIBUTION. the north side of the hill, poorly exposed and of quartz and pink orthoclase in an aphanitic red­ extreme product, exemplified in the dump of the partly concealed by a talus of massive rhyolite dish-gray groundmass, within which may occasion­ Copper King mine, is a fine-granular aggregate of The visible faults of the Bisbee quadrangle are derived from the top of the hill, is a rhyolitic ally be seen little cavities lined with projecting quartz, sericite, and pyrite, indistinguishable from most abundant within an irregular, northwest-south­ breccia, which has the general appearance of a vol­ crystals of quartz. certain altered forms of the schist. Less altered east zone that lies between Bisbee and Don Luis. canic agglomerate. Unfortunately the relations of Under the microscope the texture is found to be phases reveal traces of the original porphyritic This belt of dislocation is partly bounded on the the rhyolite and rhyolite breccia to each other and very similar to that of the finer-grained granite- texture, but the microscope shows that the quartz northeast by the great Dividend fault, which passes to the surrounding limestones are concealed by porphyries. Phenocrysts of quartz and orthoclase phenocrysts have recrystallized as granular aggre­ under Dividend Flat in the town of Bisbee and superficial detritus in this region of usually unri­ lie in a holocrystalline quartz-orthoclase ground- gates, and that the former feldspar phenocrysts brings the Paleozoic rocks on the southwest against valled exposures. But the form of the rhyolite mass. The crystallization of this groundmass is are now mixtures of quartz and sericite. pre-Cambrian schist on the northeast. The south­ mass, its vertical flow structure, and its association finely and obscurely granular, with patchy, shad­ The nature of the metarnorphic processes that western limit of the belt is similarly defined by with an agglomerate-like rhyolitic breccia suggest owy extinctions between crossed nicols and occa­ have been active in the vicinity of the intrusive another important dislocation which passes about that it is probably a small volcanic neck or plug sional minute micropegmatitic mtergrowths. It is mass of Sacramento Hill will be considered at 2^ miles northeast of Naco Junction and may be through which rhyolitic lava ascended to a pre- such a texture as is known to result from the devit­ greater length in the discussion of metasomatic called the Abrigo fault, since it is folio ived for a Cretaceous surface. rification of an originally partly glassy groundmass, processes connected with ore deposition. part of its course by the canyon of that name. About a mile northeast of Naco Junction is a and in view of the pronounced fluxion structure of Where it crosses the western boundary of the small mass of white rhyolite intrusive in Naco the rock mass this origin seems sufficiently probable AGE OF GRANITIC INTRUSIONS. quadrangle the faulted tract has a width of about limestone. The rock is remarkable for a very reg­ to justify the classification of the rock as a rhyolite As the granite and granite-porphyry have sup­ 4 miles, while between Bisbee and Don Luis it is ular and pronounced flow banding which stands (or more strictly aporhyolite) rather than a granite- plied pebbles to the Glance conglomerate and about 2^ miles wide. At Glance the zone is nearly vertical and trends with the longer axis of porphyry. But, as already pointed out, this dis­ nowhere cut the beds of the Bisbee group they are about 1^ miles wide, while southeast of that point the intrusion. This lamination is so pronounced tinction is unimportant in this region, where the evidently pre-Cretaceous. Many of the granite- it is represented by a single fault the continuation as to give the eruptive rock much the appear­ rocks here called granite-porphyry are connected porphyry dikes and the stock of Sacramento Hill of what will presently be described as the Gold ance of a white schist or shale. by direct transitions with devitrified rhyelites. are intrusive into the Naco limestone and are there­ Hill overthrust. It is probable that in this south­ Petrography. The granite-porphyry, as it occurs A partial chemical analysis of the above-described fore clearly post-Carboniferous. Although the eastern portion of the quadrangle much intricate in most of the dikes of Escabrosa Ridge, is a rhyolite is given under IV on page 7, and a com­ granitic stock of Juniper Flat is in contact with no faulting of the Paleozoic beds is concealed by the pinkish or reddish rock having a decidedly parison of this analysis with that of the granite- rocks younger than the pre-Cambrian Pinal schist, Cretaceous formations, and consequently the faults speckled appearance, which usually serves to dis­ porphyry under III shows that both are products yet from the close connection of this granite with which are visible at the surface and to which tinguish it at a glance from the other rocks of the of the same magma. the granite-porphyry, it is fair to conclude that all description is necessarily confined may constitute quadrangle. It contains corroded or idiomorphic The small intrusive mass a mile northeast of of the forms assumed by the granitic magma belong but part of 'a belt of faulted structure as wide as phenocrysts of quartz up to a centimeter in diame­ Naco Junction, already referred to, is a devitrified to one general period of intrusion, and are accord­ or wider than that west of Bisbee. ter, and generally smaller or less conspicuous phe­ rhyolite in which the original flow structure, as ingly post-Carboniferous and pre-Cretaceous. The It will be noted that the tract thus characterized nocrysts of flesh-tinted orthoclase, embedded in a seen under the microscope, has not been wholly period of eruptive activity, however, extended over by abundant faults is practically coincident with reddish groundmass that is nearly or quite aphan- obliterated by the subsequent crystallization of the a sufficient length of time to allow the solidification the present areal distribution of the Paleozoic rocks itic. Biotite in small scales is sometimes present, glassy groundmass. of the granite and of some of the granite-porphyry exclusive of the comparatively unfaulted Penn- but as a rule quartz and orthoclase are the only The important intrusive mass .of _ Sacramento dikes before they were cut by later intrusions of sylvanian limestone of the Naco Hills. minerals recognizable by the unaided eye. Hill was probably originally a granite-porphyry of the same magma. The only other important faults are a few' that There can be little doubt that the reddish color the type common along Escabrosa Ridge. But it cut the Cretaceous beds northeast of Bisbee, and OTHER ERUPTIVE ROCKS. of the porphyry, although characteristic of the has been greatly altered in a manner that will be although these are of comparatively moderate dis­ freshest rock obtainable at the surface, is a result described when the mineralization of the region At a few places within the quadrangle occur placement they receive conspicuous expression on of incipient weathering, for specimens obtained is discussed. small dikes of a gray porphyritic rock cutting the the geological map of the quadrangle from the from deep mine workings, away from oxidizing or Cretaceous beds and therefore younger than the manner in which they offset the gently inclined CONTACT MBTAMOBPHISM. mineralizing action, are light gray or pale green. granite-porphyry just described. The best exposed beds of the Mural limestone. Under the microscope the dominant phenocrysts If the ore bodies and their possible relation to dike of this class occurs at the Glance mine, cutting are found to be quartz, showing the usual embayed contact metamorphism be disregarded, it may be Glance conglomerate. It is less than 50 feet wide EXPRESSION IN TOPOGRAPHY. outlines, and orthoclase, often rendered semi-opaque said that the effect of the intrusion of the granite- and runs nearly north and south through a little The topographic expression of faults may be con­ by minute ferritic inclusions. Much less abundant porphyry into the limestones has not been conspic­ saddle just south of the mine. This dike is com­ sidered as of two general kinds, distinguished as are crystals of sodic oligoclase, usually more or less uous, and that in the case of many of the smaller posed of a light-gray rock that contains small pheno­ primitive and erosional, the latter being further altered to kaolin, and an .occasional scale of dikes it is inappreciable. In Uncle Sam Gulch, just crysts of white feldspar and biotite and superficially susceptible of elaborate analysis into many sub­ bleached biotite. In the more coarsely crystal­ above the old mine of the same name, the Naco resembles a mica-diorite-porphyry. The micro­ types. In the primitive expression of a fault, the line rock of the larger dikes the groundmass shows limestone is cut by an irregular dike of granite- scope shows phenocrysts of oligoclase partly altered upheaved block forms a ridge or hill while the both microgranitic and miropBgmatitic textures. porphyry. The contact between the two rocks is to calcite, of some mineral (pyroxene?) now altered downthrown block floors a valley, the top of the The micropegmatite usually envelopes the pheno­ well exposed in a prospect pit, and the limestone to aggregates of calcite, quartz, limonite, and other ridge and the bottom of the valley representing crysts and is commonly divided into somewhat preserves its usual color and compact texture up to secondary products, and of biotite, all lying in a the displaced portions of the surface as it existed irregular radial segments of different optical orien­ the actual junction with the intrusive rock. In groundmass composed mainly of orthoclase, which before faulting occurred. Obviously, ideal primi­ tation. At a distance from the phenocrysts the other words, it exhibits to the naked eye no appar­ is crowded with minute inclusions and extinguishes tive expression can be found only in connection groundmass is made up of quartz, orthoclase and ent metamorphism. A thin section of the lime­ in shadowy patches between crossed nicols. The with very recent faults or in regions so extremely muscovite in a fine microgranitic aggregate. In stone at the contact, shows, however, that it is rock is too much altered to repay thorough inves­ arid that erosion has been able to make but slight the less coarsely crystalline rocks of the small dikes nearly one-third altered into a granular aggregate tigation but is probably a monzonite-porhyry, progress. According to Russell's descriptions it and near the walls of the larger dikes the ground- of quartz which forms an irregular web inclosing approaching a syenite-porphyry in composition. obtains in that part of the Great Basin which is mass is often a minutely and rather obscurely crys­ residual kernels of calcite. A decomposed greenish intrusive is occasionally included in southern Oregon. In somewhat less talline aggregate of quartz and orthoclase in little In the vicinity of Sacramento Hill, the only seen in small dikes in the Paleozoic rocks south­ ideal sharpness it is probably exemplified in other micropegmatitic granules less than 0.1 mm. in diam­ place where a large body of granite-porphyry west of Bisbee. These masses are of no struc­ regions of the Great Basin, as in those ranges eter. Such porphyries are not to be sharply distin­ comes into contact with the limestones, these tural importance and are too small to map. Thin whicli led Gilbert, in the course of the Wheeler guished from those of rhyolitic habit (aporhyolites) show considerable alteration, which, however, is sections show complete alteration to aggregates of Survey, to the recognition of the well-known and in which the minutely crystalline felsitic ground- to a large extent shared by the porphyry itself. chlorite, quartz, calcite, sericite, and other second­ much discussed Basin Range type of orographic mass has resulted from devitrification of a glassy As seen in surface exposures the principal change ary products, while such vestiges of original texture structure. As"t|ie normal progress of erosion must base subsequent to the solidification of the rock. in the limestone has consisted in the replacement as remain suggest that the rocks were formerly fine­ soon soften the7 primitive expression of a fault, A chemical analysis of a representative specimen of the calcium carbonate by granular aggregates of grained diabases. and in time must greatly modify and perhaps of the granite-porphyry is given under III, on page quartz containing chlorite and pyrite. The chlo- GEOLOGICAL STRUCTURE. ' finally obliterate or reverse it, there is clearly no 7. It will be seen that it differs from the analyzed rite tends to form little ellipsoidal nests, and when sharp distinction in nature between the evanes­ specimen of the Juniper Flat granite in the great the rock is exposed to the weather the chlorite is Introductory Statement. cent condition of ideal primitive expression and preponderance of potash over soda. In this respect removed, the pyrite is oxidized, and the originally Up to this point the rocks of the quadrangle the manifold stages of erosional modification. it probably corresponds closely with the fine­ light-colored limestone becomes a rusty, cavernous, have been considered chiefly as objects of descrip­ Consequently it is often difficult or impossible to grained granite described on page 7. siliceous rock looking superficially not unlike a tion. They have been divided into natural assem­ determine whether the topographic expression of a 9

given fault should be considered as essentially relationship is extant in the Bisbee quadrangle. TRENDS AND DIPS. the Escabrosa limestone rests discordantly upon primitive or as erosional. Thousands of feet of The faults of the latter region are probably all the Martin and Abrigo limestones with an undu­ overlying beds may have been removed, and yet much older than those which have been appealed The dominant faults of the Bisbee quadrangle lating but on the whole nearly horizontal contact differences in elevation in the present topography, to in explanation of the main topographic features range in trend from northwest to west-northAvest. which is apparently the result of faulting. If so it as determined by some hard stratum in the dislo­ of the typical Basin Ranges. Such are the Dividend, Abrigo, and Gold Hill represents a slightly inclined overthrust of unknown cated formations, may continue to topographically By looking a little more closely into the manner faults, the conspicuous dislocation near the Bisbee extent and direction. register the original displacement of the fault. in which the faults of the Bisbee quadrangle have West mine (hereafter referred to as the Bisbee The dike-seamed southwest face of Escabrosa In the erosional expression of faulting in topog­ influenced erosion, considerable diversity may be West fault), and most of the dike-filled faults Ridge presents several instances of reversed faults raphy, on the other hand, the displacement is not found, as would be expected when faults constitute along the southwest face of Escabrosa Ridge. of a special kind. They are fissures now occupied directly recorded by differences in elevation of the but one factor in a complex process. As a rule Distinctly subordinate to the northwesterly frac­ by dikes of granite-porphyry, apparently intruded present surface. The fault in the typical case has the structurally important faults are rather incon­ tures, but of much structural importance, are a during the faulting. Such contemporaneous fault­ become a mere element of internal structure, intro­ spicuous at the surface, in view of the usual excel­ number of faults with northeasterly trend. Some ing and intrusion may conveniently be referred to ducing (just as do folds, intrusive masses, and vari­ lence of the rock exposures in this region. They of the more prominent of these occur within an as intrusion faulting, and the results of the action ations in the lithological character of beds) factors rarely show any appreciable silicification and are irregular zone of faulting that stretches southwest- as intrusion faults. The best examples of this of structural diversity which are neither overlooked not accompanied by the resistant siliceous breccias ward from Bisbee across Escacado Canyon and past structure are to be found close to the western boun­ nor exaggerated in the impartial work of erosion. which are so characteristic a feature of the faulting the Bisbee West mine. One of the most interesting dary of the quadrangle, about halfway between The topographic accentuation or subordination of of the Globe quadrangle, where similar rocks are members of this belt of cross faults may be traced Moores Canyon and Brown's ranch, where two the fault bears no necessary relation to the amount involved. Instead of outcropping more or less almost continuously from the vicinity of the quartz­ dikes may be seen cutting through the Abrigo, or character of its displacement, but is the accurate boldly above the surface, as in that region, the ite quarry west of Bisbee to a point half a mile Martin, and Escabrosa limestones and displacing expression of the importance of the dislocation comparatively unindurated fault breccias of the northwest of the Bisbee West mine a distance of the beds by reversed throws of 75 and 150 feet. as one of many factors determining that hetero­ Bisbee quadrangle are commonly elements of weak­ 2 miles. As there will be frequent occasion to As most of the dikes along Escabrosa Ridge dip geneity of material which in most regions of ness and as such tend to find topographic expres­ refer to this important dislocation, it may con­ to the northeast, and as the general result of the erosion is the essential condition of topographic sion as saddles, ravines, or valleys. For example, veniently be called the Quarry fault. On the faulting with which they are associated has been variety. the Dividend fault has determined in part the northeast the Quarry fault apparently ends at the to depress the country on the southwest rela­ In the Bisbee quadrangle the topographic expres­ course of Mule Gulch. The Abrigo fault is taken Dividend fault, while on the southeast it may ter­ tively to that on the northeast, the examples cited, sion of most of the faults is of a maturely erosional advantage of by Abrigo Arroyo for a distance of minate at the Bisbee West fault, although a tongue although of very moderate throw, may be taken as type, such as is well exemplified in the Dividend about half a mile, and near the western edge of the of Quaternary material unfortunately conceals the typical of the intrusion faulting of the southwest and Abrigo faults. quadrangle determines a saddle between quartzite junction of the two fractures. As a rule the north­ slope of Escabrosa Ridge. When the Dividend dislocation occurred, the hills on the north and limestone hills on the east faults in the Escacado zone are less persistent There still remain those faults for the classifica­ Final schist near Bisbee was surmounted by Paleo­ south. The positions of Black Gap and the sad­ than the dominant northwest faults and frequently tion of which the obtainable data are insufficient. zoic beds at least 5000 feet in total thickness dle at the head of Mexican Canyon are due to terminate at the latter. There are, however, several Of these the most important, and the only one that the continuation of the strata now preserved in erosion along lines of weakness resulting from short northwest faults which end against northeast need here be mentioned, is the Dividend fault. In the downthrown block on the southwest side of the faulting. The course of the Gold Hill overthrust faults, so that direction and persistency are not spite of the extensive underground work accom­ fault. Unless the movement along the fissure was is marked by a curved line of ravines and sad­ invariably related. plished in its vicinity this fault is hot well exposed so slow as not to outstrip denudation, the now- dles and by the straight open valley extending A northeast fault of considerable economic and the direction of its dip is unknown. It is vanished beds were uplifted as a mountain ridge from Glance to Christianson's ranch. importance traverses the northwest slope of Queen apparently nearly vertical, and as it is known that overlooking the downfaulted tract to the southwest. Along a few of the fault planes cliffs have been Hill and has been called the Czar fault. Others the southwest wall has gone down or the northeast But these mountains have since succumbed to ero­ developed by erosion. These are occasionally 300 of similar trend occur in Uncle Sam and Silver wall up, the determination of the particular class sion, and the limestone hills of the depressed block or 400 feet in height, and the best examples Bear gulches and still another dislocates the Paleo­ of faults to which it belongs is perhaps a merely look down upon the upheaved and denuded schists, occur on the east side of Escacado Canyon about zoic formations at Black Gap. academic matter. on which a few tiny remnants of Bolsa quartzite 14 miles northwest of Don Luis. These bold The faults cutting the Cretaceous beds northeast As a rule only the relative movement of faults remain as witnesses of the former presence of the white cliffs, which are visible from any part of of Bisbee are also to be classed with those of north­ can be ascertained. We can very rarely determine, Paleozoic series. the broad Espinal Plain, are composed of Car­ eastern trend. for instance, in a given normal fault whether the The Abrigo fault, which brings the Naco lime­ boniferous limestones which have been slightly In addition to the fissures of generally northwest­ hanging wall actually moved down, or the foot wall stone against the Bolsa quartzite on the western downfaulted against Devonian and Cambrian beds. ern or northeastern trend, the quadrangle, as is to really moved up, or whether both walls moved in edge of the quadrangle, corresponds to a throw of Very frequently it is found that faults of much be expected, presents several examples of faults opposite directions. With this clearly understood at least 3000 feet. But of this great actual defor­ structural importance and with throws of several which do not conform to either of the principal once for all, to avoid circumlocution, the hanging mation of an older topographic surface the present hundred feet have been impotent to impress their directions. For example, Queen Hill is cut by a wall of a normal fault will usually be described in topography retains no trace. presence upon the topography, whose local devel­ north-south fault, while a nearly east-west fault the following pages as dropped or downthrown and Many other illustrations of the erosional expres­ opment was in such instances controlled by other passes just south of the Cole shaft of the Lake the hanging wall of a reversed fault as upheaved or sion of faults might be drawn from the tract of structural elements. Superior and Pittsburg mine. Such dislocations overthrust. faulted Paleozoic rocks west of Bisbee, but indi­ As will be later shown, many fault-fissures in are structurally very subordinate and area neces­ vidual citation is hardly necessary, since the total the Bisbee quadrangle have been filled by dikes of sary accompaniment of the general fissuring of the AGE OP THE FAULTING. disappearance of the primitive topographic expres­ granite-porphyry. So far as the dike persists such quadrangle in two main directions. The faults of the Bisbee quadrangle may be sion of the faults may be-readily verified by refer­ a fault can be followed with comparative ease. grouped as follows: (1) those of post-Pennsyl- CHARACTER OF DISLOCATION. ence to the geological map and structure sections. Other faults in the Paleozoic rocks may be, vanian but pre-Cretaceous age, (2) those of post- As regards the faults cutting the Cretaceous beds accurately traced for long distances by one who Faults that are not vertical admit of a twofold Cretaceous but pre-Quaternary age, and (3) those northeast of Bisbee, the case is not so patent. The looks carefully for evidence of fracturing and classification based upon the relative movement of which are post-Pennsylvanian and pre-Quaternary, principal dislocation is here effected by a nearly crushing and who has gained sufficient familiarity their walls. Those along which the hanging wall but which can not be assigned with certainty to vertical fissure which passes through the saddle at with the distinctive features of the local Paleozoic has slipped down (or the foot wall risen) are known either of the two preceding groups. the head of Mexican Canyon and has elevated the formations to recognize the particular abrupt litho­ as normal faults, while those in which the hanging To the first group belong the intrusion faults beds on the southeast about 500 feet relative to logical changes which are characteristic of faulted wall has risen (or the foot wall gone down) are and the fissures so directly connected with these as those on the northwest. This fault is very evi­ structure. But when the faults traverse the Car­ known as reversed, thrust, or overthrust faults. to preclude the idea of difference in age. Such are dent to an observer looking up toward the head of boniferous limestones, as they do southwest of In the case of vertical faults, the foregoing dis­ the Dividend fault, the Quarry fault, the Bisbee Mexican Canyon from the conglomerate-filled basin Bisbee, their recognition demands close observation tinction vanishes, and the more nearly a fault West fault, and most of the faults on the southwest north of Black Gap, since it interrupts the con­ and patience. Even with good exposures it is not approaches the vertical position, the more difficult slope of Escabrosa Ridge. The nearly horizontal spicuous white band of Mural limestone, and always possible in limestones to distinguish an it may become to determine by surface exposures overthrust west of the Bisbee West mine probably as this limestone determines the outline of the important fault from an insignificant fissure the character of the dislocation. belongs here, although there is reason to believe ridge in this neighborhood, the displacement by indeed the brecciation, silicification, or mineraliza­ Both of the foregoing classes are represented in that it was formed a little earlier than the nearly the fault finds corresponding expression in the tion may be far more pronounced in the case of the Bisbee quadrangle. Faults of normal type are vertical faults in its vicinity. The Black Gap fault topography. the latter. In the Bisbee quadrangle, the great clearly exemplified by the Abrigo fault, by several certainly belongs in this group, as it dislocates the This then, taken by itself, is an example of one thickness and uniformity of the Naco limestone of the fissures along the southwest slope of Esca­ Pennsylvanian Naco limestone but not the uncon- of those indeterminate cases already referred to, and the lithological identity of certain of its beds brosa Ridge, particularly those not occupied by formably overlying Cretaceous Glance conglomerate. in which the expression of the fault may be with those of the Escabrosa limestone make the dikes, by the Quarry fault, the Bisbee West fault, To the second group are assignable the faults either essentially primitive or erosional. It is working out of the faulted structure a laborious most of the faults in the vicinity of Escacado Can­ cutting the beds of the Bisbee group. Such are probable, however, that the Bisbee quadrangle has process, entailing the unremitting collection of the yon, most of those lying between Bisbee and Don the nearly vertical faults northeast of Bisbee, sev­ been considerably eroded since this faulting never-too-abundant fossils in order to check, step Luis, and by the faults in the Bisbee group north­ eral small displacements in Mule Gulch southeast occurred, so that the expression of the dislocation by step, the structural interpretations by the evi­ east of Mule Gulch. of town, the Gold Hill overthrust with its associ­ is erosional and that its superficial resemblance to dence of paleontology. Faults of the overthrust type are remarkably ated complex minor faulting as manifested south­ the primitive type is due to the control maintained The obscurity of many of the faults in the lime­ well shown in the southeastern part of the quad­ east of Gold Hill, and the Glance overthrust. over erosion by the resistant beds of the Mural stones is well illustrated by the structurally and rangle, where limestones ranging in age from the Accompanying this post-Cretaceous faulting there limestone. This view is confirmed when study is economically important Czar fault, which traverses Cambrian to the Carboniferous have been thrust was very likely some revival of movement along made of the opposed Gold Hill and Glance over- the northwestern slope of Queen Hill, separating from opposite directions over the Cretaceous for­ the Dividend and other faults whose initial dis­ thrust faults and it is seen that the relation of the the Naco limestone of the mass of the hill from the mations by the Gold Hill and Glance faults. placements dated from pre-Cretaceous time. present topography to the faults is such as to clearly Escabrosa limestone of Hendricks Gulch. It has These, as will be fully showc in the following To the third group belong a few faults in the demonstrate a subsequent origin for the topography. a throw of probably more than 500 feet and crosses pages, are typical examples of this always impres­ Paleozoic terrane southwest of Bisbee, which are It may be concluded, then, notwithstanding the a steep hillside upon which apparently every bed sive form of dislocation, in which older rocks have not so clearly related to the granite-porphyry present aridity of climate and the many points of of limestone is exposed to view from the hotel in been thrust for considerable distances up gently intrusions as to establish conclusively their pre- geological resemblance between this part of Arizona Bisbee. Yet so slightly does it affect the appear­ inclined planes of fracture until they conspicuously Cretaceous age. The most prominent example of and the Great Basin, where the primitive topog­ ance of the bare, fume-swept hill that daily famil­ overlie very much younger beds. Other cases of these is the Abrigo fault. Although the age of raphic expression of faults has been described by iarity with the slope gives no hint of dislocation to overthrust occur in the vicinity of Abrigo Canyon these faults can not be directly ascertained, there is careful observers, that no trace of such primitive one unaware of its existence. about a mile west of the Bisbee West mine. Here nevertheless strong probability that they are of the Bisbee. 10 same age, at least so far as their initial displace­ overlapped by the Cretaceous beds comprising the The distribution of these outlying remnants of concealed by a talus of limestone and cherty breccia, ments are concerned, as the faults of the first Bisbee group, and on the northwest extends beyond Bolsa quartzite is further significant as showing its immediate vicinity is usually marked by indu­ group. Their general similarity, as regards trend, the limits of the quadrangle. It consists funda­ that the Cretaceous beds north and east of Bisbee bitable evidence of disturbance and frequently by dip, and character of dislocation, to faults known mentally of crumpled crystalline schists (Final were laid down upon an erosion surface that was an abundance of silicified limestone breccia. The to belong to this group and their lack of relation schists) partly overlain by Paleozoic formations locally very nearly coincident with the pre-Cam­ only point where the contact is clearly exposed is by the known post-Cretaceous faults afford a reas­ and cut by granitic intrusives. Structurally it is brian peneplain (see also page 12). in the western angle of the little fault block, close onable basis for deciding that the faults placed in the highest of the several simple blocks into which When the fragmentary Mount Martin syncline to the Abrigo fault, in that part of its course coin­ the first and third groups are all post-Pennsyl- the quadrangle has been divided, all the others is further examined it is seen to be dissected by cident with Abrigo Canyon. Here the shattered vanian and pre-Cretaceous in age, and that but having been relatively downfaulted. It is thus numerous faults. The most important of these Escabrosa limestone may be seen resting discord­ two general periods of faulting were concerned in the block which in the present stage of regional is one of northeasterly trend which crosses Esca­ antly above the Martin limestone and separated the structure of the Bisbee quadrangle. erosion best exhibits the crystalline pre-Paleozoic brosa Ridge about halfway between Mount Martin from the latter by a foot or more of breccia con­ With this preliminary outline of the nature and foundation upon which the stratified rocks of the and Mount Ballard. This is a normal fault which sisting of limestone fragments in a triturated red­ expression of the principal dynamic process con­ quadrangle have been piled. drops the beds on its northeast side about 250 feet. dish matrix. It is concluded from the foregoing cerned in the structure of the quadrangle, we may Of the pre-Paleozoic structure which must once evidence that the Escabrosa limestone in the vicin­ pass at once to the consideration of the whole geo­ have belonged to the rocks now known as the Final ESCABROSA BLOCK. ity of Abrigo Canyon has been thrust by a nearly logical fabric, introducing into this general discus­ schist nothing is directly discoverable. The bed­ This complex structural division is bounded on horizontal fault over the Martin and Abrigo for­ sion such further details in connection with the ded sediments from which the schists were likely the northeast by the Escabrosa zone of faults and mations. This movement evidently took place faults and such reference to folds and igneous derived by metamorphism were probably much dikes, and on the southwest by the Abrigo fault. before the nearly vertical faults now inclosing the intrusions as may be required. folded and perhaps considerably faulted; but meta- On the northwest it extends beyond the bounds of block in which it is recorded were formed. The morphic recrystallization has obliterated the direct the quadrangle and on the southeast it passes continuation of this overthrust beyond the fault General Structural Analysis. record of these processes. The present lamination beneath the Quaternary of Espinal Plain. In its block in which the observed phenomena connected DIVISIONS OF QUADRANGLE BASED ON STRUCTURE. of the Final schist is on the whole nearly vertical broadest structural aspect it may be imagined a with it are now isolated has been removed by ero­ Clearness of treatment requires us for the pres­ and the dominant strike is a little north of east; but wide step upon which one mounts from the Naco sion or carried down below the present surface ent to strip from a somewhat complex structure the dip and strike of this cleavage are extremely block and thence ascends to the Bisbee block. by later faulting. The direction and original those various details with which Nature embel­ variable, and the rock is too uniform to reveal, in The rock most extensiA^ely exposed upon the sur­ extent of the overthrust are accordingly unknown. lishes her handiwork, and to compress essentials so limited an area of exposure, any clue to the face of this block is the Abrigo limestone. The into the artificial simplicity of a diagram. In character of the pre-Paleozoic deformation. general dip of these beds is southwesterly, but NACO BLOCK. the fault diagram sheet the quadrangle has been The granite mass of Juniper Flat and the smaller they are usually gently folded, the axes of the This unit, lying on the southwest or downthrown roughly divided into several structural blocks or granite-porphyry body of Sacramento Hill, both folds striking northwest and southeast. In the side of the Abrigo fault, is structurally the most tracts. On the northeast and southwest are the of which are important structural elements of the vicinity of faults and dikes the Abrigo beds often simple of the divisions into which the quadrangle broadly spread Quaternary deposits of Sulphur Bisbee block, have the typically irregular forms of show local departures from the prevalent strike has been diagrammatically divided. Its exposed Spring Valley and Espinal Plain, which effec­ intrusive stocks. The comparatively simple south­ and dip, and near the Escabrosa fault-and-dike portion consists of Naco limestone cut by two small tually conceal the underlying rocks in these quar­ west boundary of the Juniper Flat stock and its zone the beds pass as a rule through rapidly masses of rhyolite. The beds have the form of a ters. Between Bisbee and Sulphur Spring Valley, approximate parallelism with the dominant dikes increasing steep southwesterly dips into a nearly gently arched anticline pitching at an angle of 10 stretching from the top to the bottom of the dia­ and faults of Escabrosa Ridge indicate that the vertical attitude. to 15 degrees to the north, but becoming nearly gram, is the main Cretaceous tract, occupied by the intrusion took place along a northwest-southeast The other formations exposed in this block are horizontal near the Abrigo fault. Upon this gen­ rocks of the Bisbee group broad at the north but fault or fault zone. The evident relation of the the Final schist along the northeastern margin, the eral anticline are superposed slight minor corruga­ constricted in the south by the Gold Hill and Sacramento Hill mass to the Dividend fault Bolsa quartzite, and the Martin, Escabrosa, and tions with various axial trends. The Abrigo fault, Glance overthrusts. Here blocks consisting in their shows that here, also, intrusion was facilitated by Naco limestones, all constituting a mosaic of minor wnich bounds the block on the north, is a simple lower part of Paleozoic strata but bearing Creta­ faulting. Something more than simple faulting, fault-blocks, diversified by dikes and sills of granite- dislocation with a southerly dip of about 75 degrees. ceous beds on their backs have been thrust toward however, is necessary to explain the irregular inva­ porphyry. The throw is normal arid amounts to rather more each other from nearly opposite directions through sion of the schists and Paleozoic rocks by the gran­ The Escabrosa zone of faults and dikes is far than 2000 feet. The fault is well exposed in and over the Cretaceous beds. itic magma. There is no evidence that the latter from being the simple line of dislocation indicated Abrigo Canyon, where it is associated with a Extending from the northwest corner of the dia­ fused and assimilated the invaded rocks in the in the diagram. It is a complex belt of branching breccia of crushed limestone. gram past Bisbee is outlined an area of Final schist vicinity of the contact. It must therefore be con­ and reticulating dikes and faults. The net result representing the largest exposure in the quadran­ cluded that the magma made place for itself either of the faulting along this zone has been to drop the COPPER QUEEN BLOCK. gle of the ancient pre-Cambrian foundation of the by forcing the encircling rocks aside or upward, or Escabrosa block with reference to the Bisbee block. Economically, this is by far the most important region. It is shown as cut by the granite stock of by the process of block engulfment. So far as The total throw can not be exactly determined. It structural division of the quadrangle, as within it Juniper Flat and by the smaller granite-porphyry available evidence goes, either or both of these is over 2000 but probably less than 2500 feet. occur all of the productive copper deposits known stock of Sacramento Hill. The latter is indicated processes may have been operative in the case of Northwest of Abrigo Canyon the dislocation has in the Mule Mountains. On the northeast it is as of later origin than the Dividend fault. the Bisbee intrusions. been effected mainly by intrusion faults of the bounded by the Dividend fault, the granite-por­ South of the pre-Cambrian schist area is a trian­ In that portion of Escabrosa Ridge which is sur­ reversed type. Southeast of Abrigo Canyon, how­ phyry stock of Sacramento Hill, and, superficially, gular area of Paleozoic beds characterized by a mounted by Mounts Martin and Ballard, and which ever, the greater part of the displacement occurs by the overlapping Cretaceous beds of the Bisbee gentle southwesterly dip. The relation of these corresponds to the triangular area indicated in the along the Bisbee West fault, which is normal in group. ' On the northwest it is cut off by the beds to the schists north of them is that of uncon- diagram between the Quarry fault and the Esca­ type. The faults of the Escabrosa zone are occa­ Quarry fault. On the southwest it is limited by formable deposition. brosa zone of faults, is preserved a section of sionally opposed in throw. For example, the the Bisbee West fault of the Escabrosa zone and is The schists, the intrusive masses, and the trian­ the Paleozoic rocks wljich is complete very nearly Mount Martin syncline is cut off, half a mile partly overlapped by Quaternary deposits. On gular area of Paleozoic beds are all included in a to the top of the Escabrosa limestone and rests southwest of the summit of the peak, by an intru­ the southeast it disappears beneath the Gold Hill single structural unit, which has been distinguished unconformably upon the crystalline basement of sion fault which has dropped the beds to the north­ overthrust. in the diagram as the Bisbee block. the Final schist. These beds dip generally to the east of it, thus counteracting in part the prevalent- In its broader structural aspect .the Copper On the southwest the Bisbee block is separated southwest at an angle of about 25 degrees, but southwest downthrow of the zone as a whole. Queen block is a fragment of a canoe-shaped syn­ diagrammatically by a simple line, representative southwest of Mounts Martin and Ballard, where Just north of Abrigo Canyon the Escabrosa cline having a nearly north west-southeast axis that of the complex zone of faults and dikes along they are cut off by the faults of the Escabrosa block is transversely divided by a nearly north­ pitches southeastward. The northwestern limb of Escabrosa Ridge, from an area of Paleozoic rocks zone, they become horizontal or dip slightly to east-southwest fault with downthrow to the south­ this syncline, cut off by the Dividend fault and possessing a general southwesterly dip. This has the northeast. They thus constitute a fragment of east. The throw of the fault is probably nowhere relatively upheaved, has been removed by pre-Cre­ been called the Escabrosa block and with reference the northeast half of a gentle syncline having a more than 500 feet, but it is sufficient to bring the taceous erosion. In the down-dropped Copper to the Bisbee block is downfaulted. northwest-southeast axis and a southeasterly pitch. Escabrosa limestone in contact with Abrigo beds. 'Queen block is preserved the northeastern end of Southwest of the Escabrosa block, separated from Outlying remnants of Bolsa quartzite, formerly Inclosed between this fault, the Bisbee West fault, the southwestern half of the original synclinal it by the Abrigo fault, is the Naco block of gently parts of this syncline, occur perched along the the Abrigo fault, and some 'hiinor faults to the canoe. folded Pennsylvania!! limestone. With reference crest of Escabrosa Ridge for some distance beyond southeast is a block a little over 1^ square miles In this structure are represented all of the pre- to the block northeast of it this mass represents a the western boundary of the quadrangle, showing in area in which are exposed the Abrigo, Mar­ Cretaceous rocks of the quadrangle. At the bot­ further important downthrow to the southwest. that the present crest of the ridge northwest of tin, and Escabrosa limestones. The Martin lime­ tom is the Final schist, bent downward into a basin The remaining area of Paleozoic rocks distin­ Mount Ballard corresponds approximately to the stone overlies the Abrigo formation in its usual by the forces which produced the syncline. This guished in the diagram is, that designated the bottom of this structural trough and to the old conformable position, but the Escabrosa limestone, basin is lined by the Bolsa quartzite. Above the Copper Queen block, lying south of the Dividend Paleozoic surface of erosion. This same ancient as may be seen from the map, rests unconformably quartzite in successive layers, lie the Abrigo, Mar­ fault and extending eastward to the Gold Hill surface can be identified on the northeast side of upon both the Martin and Abrigo limestones. tin, Escabrosa, and Naco limestones, the latter fill­ fault. Structurally this is "a fragment of a syn- Mule Gulch by a few outlying remnants of the Such a relation may result either from erosional ing up the central part of the depression to the cline. Its relation to the Bisbee block is that of a Bolsa quartzite one on the hilltop just north of unconformity or from faulting. If from the present surface of erosion. Finally, the Sacra­ downfaulted mass. Its relation to the Escabrosa Bisbee and four at lower altitudes east of the Sac­ former, then it implies post-Devonian deforma­ mento Hill stock is an eruptive mass that has block is that of an upheaved mass. Its relation to ramento Hill porphyry mass. These remnants tion and erosion of such intensity as may fairly broken up through the schists and the overly­ the Gold Hill block is that of the underlying mass were formerly connected, probably through an be considered incompatible with the apparent con­ ing Paleozoic beds on the line of the Dividend over which the latter has been partly shoved. intervening anticline, with the Mount Martin syn­ formity that elsewhere in the quadrangle prevails fault, which is nearly coincident with the synclinal Comparison of the diagram with the geological cline, and their present positions indicate that the between the Devonian and Mississippian beds. The axis. map at this stage of the discussion will not only Dividend fault terminates on the west at its junc­ hypothesis of a fault is further supported by the In spite of the complexity introduced by fault­ aid in comprehension of the latter but will give tion with the Quarry fault. In other words, that noticeable and unusual brecciation of the superin­ ing, the syncline is distinctly recognizable in the some idea of the intricate mass of structural detail part of the Copper Queen block between the Divi­ cumbent Escabrosa beds in the immediate vicinity accompanying geological maps. The thick axial which must now be adjusted to the bare framework dend and Quarry faults may be likened to the first of Abrigo Canyon, and the development of much core of Naco limestone extends southeast of Bis­ of a diagrammatic conception. wedge-shaped slice cut from a circular cake. This secondary chert along what appear to have been bee along the south side of Mule Gulch. This conclusion is supported by the absence of any evi­ nearly horizontal planes of movement in the lime­ is inclosed on the west and south by successive BISBEE BLOCK. dence to show that either of these important faults stones above the supposed main fault. Although faulted bands which, beginning at the Dividend The Bisbee block is bounded on the southwest continues into the Final schist beyond their meet­ the contact between the Escabrosa limestone and fault west of Bisbee and sweeping in a strong and southeast by faults. On the northeast it is ing point. the underlying Martin and Abrigo beds is usually curve around \tlie pitching end of the syncline 11 toward Gold Hill, represent the outcrops of the Devonian member of the syncline. At the high­ Glance conglomerate and its face is apparently As movement along the fault continued the Escabrosa, Martin, Abrigo, and Bolsa formations est point on the ridge between Uncle Sam Gulch nearly vertically under the outcrop of the fault on Paleozoic rocks of the hanging wall were thrust conforming in general strike and dip to the syn­ and Escacado Canyon the Naco limestone rests the hillside above. The fault itself has not been forward and upward until they pressed against clinal structure. Lastly, in the southwest corner with southeasterly dip conformably upon the Esca­ reached, but the conglomerate near the face of the the Cretaceous beds northeast of Gold Hill and of the Copper Queen block, about a mile and a brosa. There are many faults between this point tunnel is greatly sheared and crushed. The squeezed them into a closely compressed anti­ half northwest of Don Luis, the fundamental and the hill north of the Whitetail mine, most of approximate line of the fault can be readily fol­ cline in the immediate vicinity of the fault. The Final schist is exposed in a few small fault blocks. which drop the beds on their northwest sides and lowed along the north slope of Gold Hill, where it effect of the thrust appears also to have been When the Copper Queen block is more closely thus tend to diminish the southeasterly pitch of has a rather steep dip to the south and is accom­ recorded, at a distance from the fault, in the change scrutinized it appears that the syncline constituting the Copper Queen syncline. Faulting of this kind panied by much crushing and disturbance of the of strike and upturning of the Mural limestone near its dominant feature may be distinguished from a has enabled erosion to expose the top of the Esca­ underlying conglomerate and overlying Escabrosa the Easter Sunday mine. It is probable that the minor structural division of the block occupying brosa limestone in two small areas in Silver Bear and Naco limestones. In the saddle northeast overthrust Paleozoic beds never extended much the triangular area including and lying west of Gulch. Had there been no faulting the dip of of the hill, the Glance conglomerate has been farther to the northeast than the present outcrop Escacado Canyon and inclosed between the Quarry the beds would have carried the Escabrosa much squeezed between the upthrust limestone and the of the fissure. The steep dip of the fault where and the Bisbee West faults. This area is charac­ deeper in this part of the syncline. mass of Cretaceous beds northeast of it into a actually exposed and the nature of the local fold­ terized by many vertical or normal faults, some of In the vicinity of the Whitetail mine the forma­ closely compressed local anticline. On the south­ ing and squeezing of the Cretaceous beds in its which have throws of over 1000 feet. It corre­ tions making up the syncline are exposed in fairly east side of the hill the thrust fault is exposed vicinity are phenomena to be expected along the sponds to a downthrown block with reference to regular succession from the Final schist on the in some prospects and exhibits a local southwest­ plowing front of a rigid overthrust mass rather the Bisbee block and to the synclinal part of the southwest to the Naco limestone that on the north­ erly dip of 50 degrees. The Cretaceous beds upon than in those portions of the foot wall which have Copper Queen block. Owing, however, to its east forms the upper part of the triangular hill upon which the overthrust Paleozoic rocks rest are much been greatly overridden. internal faulted structure the amount of this rel­ which is a bench mark at an elevation of 6320 disturbed in the immediate vicinity of the fault. ative downthrow is variable. It is slight in the feet. On the southwest slope of this hill the Naco They are crushed and sheared and in some places GLANCE BLOCK. southern part of the triangular area, where Cam­ limestone lies in undisturbed conformity upon the metamorphosed to a much crumpled, greenish seri- This is a well-defined overthrust mass that brian and pre-Cambrian rocks prevail, but is very Escabrosa. But there has been faulting between citic schist, very similar in appearance to some of emerges from beneath the Quaternary deposits of much greater in the northern part, where Penn- the latter and the Martin formation. The exact the vastly older Final schist. Sulphur Spring Valley and rests upon the Mural sylvanian limestone composes most of the sur­ nature of the movement is somewhat obscure, but We may pass for the moment the very compli­ limestone northeast of Glance station. The block face. This minor structural division may be con­ the Escabrosa formation seems to have slipped cated corner just southeast of Gold Hill and con­ consists ofNaco limestone in nearly horizontal beds, sidered as a marginal portion of the Copper Queen down along a surface of dislocation that nowhere tinue to follow the course of the main overthrust. unconformably overlain by Glance conglomerate. block, from which it became detached and fault- departs greatly from the bedding planes. A This swings through a saddle half a mile southwest It has been thrust from the east over the Mural shattered in the general dislocation of the quad­ movement of the same kind has occurred between of Black Knob and thence down past Glance sta­ limestone by a fault that is parallel to the bedding rangle at the close of the Carboniferous; or it may the Martin and the Abrigo limestones at the tion. While it is not always clearly exposed, the of the latter. The outcrop of this fault plane is be- regarded as one or more structural units of Whitetail mine. tracing of its approximate course presents no diffi­ marked by a slight topographic bench and the equivalent rank, although inferior in size, to the North of Don Luis, in the vicinity of the Cole culty, owing to the signal discordance in lithology presence of a distinct fault breccia. The dip of larger structural divisions recognized in the accom­ shaft of the Lake Superior and Pittsburg mine, the and structure of the rocks it separates and the the fault is about 25 degrees to the east. panying diagram. syncline is modified by a group of faults of various visible signs of disturbance that accompany it. Owing to the covering of Quaternary deposits Where faults are as numerous as in the Bisbee trends, and a normal dislocation, probably of over South of Glance the fault comes to the surface the geological structure that gave rise to this dislo­ quadrangle, descriptive reference to each feature 1000 feet throw, occurs between Black Gap and the along the bottom of the open valley that extends cation and the horizontal extent of the overthrust is out of the question. Although, owing to their pass through which the railroad runs from Don southward past the Glance mine, and is not very can not be determined. It was evidently effected important relation to economic problems, the dis­ Luis to Bisbee. Although this fault is conspicu­ well exposed. The dip is to the southwest as usual by forces operating along nearly east-west lines. locations of the Copper Queen syncline will be ously apparent on the south side of the ridge, but its amount is unknown. It is probably about It is likely that the Naco limestone of this block described somewhat fully, yet for many of the which it crosses, its northwestward course through 40 degrees. It is noteworthy that throughout its was ordinarily thrust forward until it met the details of structure the geological maps and sec­ the Naco limestone is rather obscure, and it has course the Gold Hill fault actually outcrops with Naco beds of the Gold Hill block advancing tions must be left to speak for themselves. not been traced beyond the point where it is a somewhat steeper dip than might be expected from the southwest. The meeting of these resist­ The greater part of Queen Hill, including the covered by Quaternary deposits. It may join one from the general character of the overthrust. It is ant masses probably formed a competent arch over summit and southeastern slope, is composed of beds of the faults mapped in the vicinity of the Cole probable that this dip becomes less beneath the the Morita beds of Black Knob and put a stop to of Naco limestone. Instead of dipping to the shaft, the two ending at the junction as do the mass of the block and that its steepness near the the nearly opposite movements of the two over- southeast, as they should were they strictly con­ Quarry and Dividend faults. present exposures of the fault is local and due to thrust blocks. formable to the general synclinal structure, these East of the fault just noted the beds composing causes that will be later pointed out. CRETACEOUS TRACT. particular beds constitute a little local syncline the Copper Queen syncline, except for a moderate A return may now be made to the faults south­ with northwest-southeast axis, as may be seen upon displacement at Black Gap, retain their normal east of Gold Hill, already mentioned. These fea­ This, the largest of the several areal units into viewing Queen Hill from the north or from the synclinal structure up to the point where the tures are not well exposed as a whole, and the which the quadrangle has been diagrammatically vicinity of Sacramento Hill. This structure, how­ structure disappears beneath the Gold Hill over- complicated structure to which they give rise may divided, is not, like the others, a definite structural ever, is very local and passes by change of dip, in thrust. These beds do not exhibit the changes in be variously interpreted. The explanation most in block. the vicinity of Uncle Sam Gulch, into that of the strike and dip that are characteristic of the curved, harmony with the facts obtained in the course of On the north it is an area within which the pre- main syncline. North and west of Queen Hill are northwest-pitching bow of the synclinal canoe, but a minute investigation of this particular area is Cretaceous structure is hidden by the overlying several faults that complicate the general structure constitute part of the straight side. briefly as follows: The offsetting of the Gold beds of the Bisbee group, with their gentle folds of the Copper Queen syncline. The lower part of Hill overthrust and the cutting out of the Glance and moderate normal faults. Its western boun­ Hendricks Gulch, including the old open cut of GOLD HILL BLOQK. conglomerate southeast of Gold Hill are due to dary is here the sinuous eroded edge of the Glance the Copper Queen mine, are in Escabrosa lime­ This structural unit is bounded on the north nearly east-west normal fault with southerly dip. conglomerate, which rests with low northeasterly stone. Instead, however, of passing conformably and east by the Gold Hill overthrust fault. On This fault is younger than the overthrust. About dip upon granite, schist^ and limestone and con­ beneath the Naco limestone of Queen Hill, the the west it passes beneath Quaternary deposits and a mile southeast of Gold Hill is a little mass ceals the northeastern extensions of the Bisbee and Escabrosa is separated from the latter by the Czar on the south extends into Mexico. Superficially of Mural limestone inclosed by faults. It occurs Copper Queen blocks. Its eastern boundary is the fault. This dislocation has dropped the Naco it is composed for the most part of Cretaceous beds with small fault blocks of the Martin and Morita similarly overlapping but less indented edge of the limestone for a distance of over 500 feet, so that it arched into an anticline with northwest-southeast formations in the axis of the Cretaceous syncline, Quaternary deposits. abuts against the Escabrosa limestone, which strati- axis. These beds lie upon a Paleozoic and per­ where normally only Glance conglomerate would On the south the Cretaceous tract appears as graphically belongs below it. The head of Hen­ haps in places upon a pre-Paleozoic foundation, be expected. It apparently extends beneath the a narrow strip superficially constricted by the dricks Gulch is in a block of Naco limestone which which is exposed along the northeastern edge of Martin limestone and is a part of the Gold Hill opposed Gold Hill and Glance overthrusts and has been faulted down into the Escabrosa. . One the block. The block rests, at least in part, upon overthrust block. The only conclusion possible is overlapped on the east by the Quaternary deposits of the faults bounding this block continues north- Cretaceous beds. It owes its position to faulting. that it was derived from the overridden and buried of Sulphur Spring Valley. northeastward to the Dividend fault near Castle The entire block has been thrust from the south­ southwest limb of the Cretaceous anticline and The outline of the tract is thus conditioned by Rock and effects a conspicuous displacement of the west up a gently inclined, undulating fault frac­ was formerly part of the beds in that limb cor­ erosion, by Quaternary overlap, and by low angle Escabrosa and Martin limestones. Between this ture for a distance that can not be accurately deter­ responding to those now exposed in the north-, overthrusts. Its internal structure has already north-northwest fracture and the Quarry fault are mined but is thought to be at least 2 miles. east limb in the vicinity of Black Knob. If been briefly described. other important dislocations which drop Martin Before the mechanics of the fault are discussed the anticline was originally fairly symmetrical this Summary of Structure. and Escabrosa beds of the Copper Queen syncline the evidence for its existence will be briefly pre­ little block of Mural limestone must have been against the stratigraphically lower Abrigo lime­ sented. The contact between the Paleozoic rocks shoved by the Gold Hill overthrust for a distance In the development of the geological structure of stone. The general effect of these faults is to and the Cretaceous rocks lying to the north and of at least 2 miles from the southwest. It thus the Bisbee quadrangle faulting has been the domi­ locally increase the southeasterly pitch of the main east is so related to the topography as to indicate affords an approximate measure of the minimum nant factor. Folding, while it has produced syncline. that the older rocks overlie the younger rocks. A amount of overthrust. important results, has been a less conspicuous The beds of Martin limestone, from which are view of Gold Hill from the northwest strongly The mechanical conditions under which the Gold process. carved the picturesque turrets of Castle Rock, in reinforces this suggestion (see fig. 11). A view of Hill overthrust was initiated can not be satisfactorily A large number of the faults are of post-Penn- the western part of Bisbee, are apparently in their the hill from the southeast is scarcely less striking, determined. As the Paleozoic strata are involved, sylvanian but pre-Cretaceous age, a lesser num­ normal stratigraphic position beneath the Esca­ and the same relation is apparent to one looking the forces concerned were by no means superficial, ber are post-Cretaceous but pre-Quaternary, while brosa beds of Hendricks Gulch, but the contact is northwest from Glance station. Close examina­ and it is unsafe to conclude that the locus and char­ some can not be definitely classified with either of not exposed and the two formations may be sepa­ tion confirms the hypothesis suggested alike by acter of the faulting were determined by any pre­ these groups, although known to be post-Pennsyl- rated by a fault. distant views and by the areal distribution of the existing structure in the Cretaceous beds. The vanian and pre-Quaternary. The pre-Cretaceous In Uncle Sam Gulch, south of Queen Hill, rocks with reference to the topography.. Wherever most that can be said is, that the overthrust was faults are the more numerous and important. They erosion has cut through the Naco formation and the contact between the Paleozoic and Cretaceous effected by strong compression acting along north­ are for the most part nearly^ vertical and include exposed a triangular area of the underlying Esca­ rocks is exposed the former are found to overlie east and southwest lines. There is reason to believe both normal and reversed types. There .is, how­ brosa limestone in its normal stratigraphic position. the latter and to be separated from them by a zone that the hanging -wall of the fault has been thrust ever, at least one flat thrust fault that is referable to Higher up the gulch, above the Uncle Sam mine, of fracturing and brecciation. On the northwest over the foot wall for a distance of at least 2 miles, this pre-Cretaceous group. . The trends of the more are two small areas of Martin limestone, showing side of Gold Hill a tunnel has been run from Gold but nothing can be learned of the antecedent struc­ important-of these earlier faults range from north­ that erosion has in places cut through to the Gulch into the hill. The tunnel is entirely in tural conditions that determined the fracture. west to west-northwest. These dominant faults Bisbee. are associated, however,"""with a number^of minor Paleozoic and Later History. Naco limestones. It is concluded that the deposi­ lowland? Was the plain formed prior to the sub­ faults having northeasterly trend. tion of limestone continued without interruption mergence by ordinary subaerial erosion at a gener­ PALEOZOIC SEDIMENTATION. The most prominent post-Cretaceous disloca­ from the Mississippian to the Pennsylvania!! ally lower level than the neighboring limestone tions are thrust faults of northwesterly trend, With the opening of Cambrian time this plain epoch. The depth of the water probably grad­ hills, and was it subsequently elevated with refer- which have shoved Paleozoic beds over Cretaceous sank beneath the sea. The waves, as the shore line ually decreased as a consequence of the steady erence to the latter, by faulting? Or was it cut beds. Less conspicuous are normal faults of encroached upon the land, rounded the fragments, accumulation of thousands of feet of calcareous during the subsidence by the combined attack of northeasterly trend. chiefly of vein quartz, that lay upon the subsiding material. It is probable, too, that there was a rain, streams, and waves upon the highest portion None of the faults in the area find primitive land surface, added to them such coarse material as general elevation of the sea bottom or of a not of the land mass and the last to be covered by the expression in the topography. The present sur­ they produced by direct attack upon the schists, very distant land mass, for fine terrigenous sedi­ sea? face is the work of erosion acting upon a geolog­ and spread the detritus evenly over the sea bottom ments are occasionally found intercalated between Reference to the geological map of the quad­ ical fabric whose heterogeneity is only in part due as the basal conglomerate of the Bolsa quartzite. the beds of the Naco limestone, as they are in the rangle shows that the line of abrupt change to faulting. As the shore advanced inland the quartzite was Martin formation. between the comparatively thin uniform layer of Amid the innumerable blocks into which the deposited as sand above the conglomerate in the conglomerate on the north and the locally thick pre-Quaternary rocks of the Bisbee quadrangle deeper water of the outer littoral zone, to a thick­ POST-CARBONIFEROUS DEFORMATION AND EROSION. and variable conglomerate on the south coincides have been divided by this complex dislocation, it ness of 430 feet. With the close of the Carboniferous period the with a line of faulting which brings the Naco is possible by the elimination of detail to recognize Then a change took place. Either there was an long era of Paleozoic sedimentation, during which limestone against small remnants of the Bolsa certain dominant structural units. These are (1) increased subsidence which carried this part of the deposits had piled up to a thickness of over 5000 quartzite resting upon the Pinal schist, and which the Bisbee block, (2) the Escabrosa block, (3) the sea bottom beyond the reach of littoral currents feet, or approximately a mile, came to an end. is the easterly continuation of the great Dividend Naco block, (4) the Copper Queen block, (5) the having sufficient power to transport sand, or the Orogenic forces became dominant and the region fault that passes through the town of Bisbee. It Gold Hill block, (6) the Glance block, and (7) nearest land mass still remaining above water no of the Bisbee quadrangle was elevated above sea is probable, therefore, that this fault had a direct the Cretaceous tract. longer supplied arenaceous sediments. The Bolsa level. To this elevation, faulting, folding, and influence upon the development of the pre-Creta­ Broadly considered, the Bisbee, Escabrosa, Naco, formation, was succeeded by the siliceous calcareous igneous intrusions all contributed. ceous topography. As is elsewhere shown (p. 9), and Copper Queen blocks are essentially masses of muds of the Abrigo formation, 770 feet in thick­ The beds appear to have been first rather gently the main displacement along this fissure was accom­ pre-Cretaceous rocks bounded wholly or in part by ness. Here, for the first time in this region, marine folded by forces acting in a northeast-southwest plished before the intrusion of the porphyry and faults of the earlier period. In detail, however, life made its appearance, for in the impure, cherty direction. There was some overthrust faulting, as consequently before the Cretaceous submergence; they are themselves dissected by minor faults, and Abrigo limestones are inclosed pteropods, abundant is shown by the sliding of the Escabrosa over the but there has also been a revival of movement their boundaries are in some cases broad and com­ fragments of trilobites, and small -Lw^w/a-likebrach- Martin and Abrigo limestones in the vicinity of along the fault since the Glance conglomerate was plex fault zones instead of simple dislocations. iopods. An incursion of white quartz-sand, now Abrigo Canyon. This was closely followed by deposited, as may be seen from the offsetting of With reference to the Bisbee block, the Esca­ consolidated as the upper bed of the Abrigo forma­ the nearly vertical normal faults and the reversed the latter formation along Mule Gulch. brosa block has been dropped from 2000 to 2500 tion, marked the close of Cambrian sedimentation. intrusion faults which constitute the salient fea­ It seems probable, in the light of all the known feet, while with reference to the latter block the Probably at no time during this period was the tures of the pre-Cretaceous structure. The intru­ facts, that the deposition of the Glance conglom­ Naco block has also been dropped about the same local sea bottom depressed to a very great depth, sion of the Juniper Flat and Sacramento Hill stocks erate was preceded and conditioned by the follow­ amount. Structurally, therefore, these three blocks and it appears to have been only occasionally cut accompanied or immediately followed this general ing train of events: After the main dislocation of constitute gigantic steps rising from the southwest off entirely from the finer terrigenous silts. faulting. the Dividend fault, subaerial erosion continued to to the northeast. Neither the Ordovician nor the Silurian period, degrade the region until nearly all of the Paleozoic MESOZOIC SEDIMENTATION. The Copper Queen block, comprising a frag­ so far as known, has left any record in the Bisbee rocks had been stripped from the up-faulted north­ ment of a canoe-shaped syncline of Paleozoic beds, quadrangle, the fossiliferous beds of the middle During Triassic and Jurassic time the moun­ east half of the quadrangle and the pre-Cambrian is down thrown with reference to the Bisbee block, Cambrian Abrigo limestone being succeeded with tainous country elevated by the post-Carboniferous schists, with their included granitic intrusives, had but less so than is the Escabrosa block. Econom­ no visible stratigraphic interruption by the Martin deformation was subjected to erosion. If any sed­ been laid bare as a broad and topographically sim­ ically this block is the most important structural limestone, carrying abundant characteristic Devo­ iments were deposited within the quadrangle dur­ ple ridge whose upper surface was nowhere greatly division of the quadrangle, as within it occur all nian fossils. In spite of the apparent conformity, ing these periods they were removed prior no the above or below the surface of the denuded Cam­ of the known important deposits of copper ore. however, the absence of the Ordovician and Silurian opening of the Cretaceous and have left to trace of brian peneplain upon which the Bolsa quartzite Within each of these blocks the beds are folded. can be satisfactorily accounted for only by suppos­ their former presence. Erosion had stripped most had been deposited. The southeastern half of the The axes of the folds usually have northwesterly ing that an interval of erosion separates the Cam­ of the Paleozoic beds from the elevated fault block quadrangle, on the other hand, with its intricate trends, although there is much local irregularity, brian and Devonian formations that is, there is an northeast of the Dividend fault and reduced the structure of downfaulted Paleozoic beds, was carved complicated by minor faulting. actual although locally imperceptible unconform­ quadrangle as a whole to a moderately hilly region into a complex hilly topography that stood as a The Gold Hill and Glance blocks are essentially ity. Any other explanation meets with insuperable when the Cretaceous period was introduced by a whole somewhat lower than the schistose terrane masses of Paleozoic and younger beds which have obstacles. The existence of such an unconformity general subsidence during which the Glance con­ to the northeast. The region was then rapidly been thrust toward each other, from the southwest is indicated by the similar conditions described by glomerate was laid down as a coarse littoral deposit submerged until the schists and granite of the and east respectively, over the beds of the Creta­ Walcott in the Grand Canyon of the Colorado, along a marine shore line that rapidly encroached northeastern part of the quadrangle alone stood ceous Bisbee group. about 350 miles northwest of Bisbee, where Ordo­ upon the land. The comparative rapidity of the above the sea. During this subsidence the cal­ The Cretaceous tract is less a definite fault block vician and Silurian beds are absent and the Devon­ submergence is shown by the variable size and careous conglomerates of the Glance formation than an area of relatively little disturbance as com­ ian is separated by an erosional unconformity from very incomplete rounding of the pebbles. These accumulated over the uneven surface of the Pale­ pared with the other structural units of the quad­ the underlying Cambrian Tonto group. It must were evidently subjected for a brief time only to ozoic rocks. Possibly, also, renewed movement rangle. be noted, however, on the other hand, that Lind- the wear of the waves and were then buried along the Dividend fault may have somewhat GEOLOGICAL HISTORY. gren (Clifton report, in preparation) has described beneath the fine gravels, sands, and muds of the accentuated the physiographic boundary between the Ordovician of the Clifton district, about 100 Morita formation. Further evidence that the sub­ the northeastern and southwestern parts of the Major Divisions. miles a little east of north fr,om the Mule Moun­ sidence was, locally at least, a geologically rapid quadrangle. There was probably at this stage a The geological history of the Bisbee quadrangle tains, as overlain conformably by the Devonian. movement is found in the hilly topography that retardation of the general subsidence, while the is divisible into three grand eons (1) that of pre- But the presence of Ordovician beds at Clifton, underlies a considerable part of the Glance for­ waves and streams attacked the still projecting Cambrian sedimentation, deformation, and meta- even if conformably beneath the Devonian, is evi­ mation. The pre-Cretaceous surface sank beneath schist mass and gradually reduced it to-sea, level, morphism, (2) that of pre-Cambrian erosion, and dence for rather than against pre-Devonian ero­ the waves before the latter could reduce its inequal­ the material derived from its degradation helping (3) that embracing the Paleozoic, Mesozoic and sion at Bisbee, where such beds are lacking. It is ities by planation or do more than slightly rework to level up the hollows in the region that was car­ later eras. one of many facts tending to show that the earlier the stony detritus that littered its slopes and lay ried down in the more rapid sinking, and finally Paleozoic sedimentation of Arizona was accom­ in its hollows. accumulating as a relatively thin deposit over the Fre-Paleozoic Sedimentation and Deformation, panied by great diversity of local conditions. The final result of the deposition of the Glance last land to become sea bottom. With the entire The dim, timeworn record of the oldest eon Whatever may have been the conditions during conglomerate was to level up the pre-Cretaceous submergence of the region embraced in the quad­ is found in the Pinal schist. It has been shown the Ordovian and Silurian, in the Devonian period topography, which* must have exhibited differences rangle the deposition of the Glance conglomerate that this formation probably consisted originally of the quadrangle was covered by an open sea of mod­ in elevation amounting to at least 600 feet, to a came to an end, and was followed by the accumu­ sediments. It follows that these were derived from erate depth, in which flourished abundant marine smooth sea bottom upon which w'ere afterwards lation, upon a gradually sinking sea bottom, of still more ancient rocks and were deposited in a organisms that contributed their calcareous parts accumulated the regular beds of the Morita forma­ 1800 feet of sands and muds composing the Morita pre-Cambrian sea. Long before Cambrian time to form the Martin limestone. That there was still tion. The filling necessary to effect this leveling formation. This is a shallow-water deposit and these sediments were altered to crumpled crystal­ a land mass rising above the Devonian sea at no was, however, as has already been pointed, out, records conditions intermediate between those line schists and were therefore presumably deeply great distance from the tract of deposition now much greater in the southern half than in the under which the littoral Glance conglomerate buried beneath other rocks and intensely folded under consideration is shown by the occasional northern half of the quadrangle, and some expla­ was formed and those represented by the Mural and compressed. As a result of such folding they occurrence of shales within the Martin formation. nation of the abrupt change which occurs along limestone. The actual source of the Morita sedi­ were probably elevated as a,n extensive mountain Walcott has shown that in the Grand Canyon the line of Mule Gulch is necessary to fully ments is unknown. It is evident that the Pinal mass. region there was an interval of erosion between elucidate the manner in which deposition pro- schist contributed detritus to the basal beds, but as the Devonian and the Carboniferous periods. ceded. it is probable that all of the schists within the Pre-Paleozoic Erosion. The evidence available in the Bisbee quadrangle is If the Cretaceous beds could be restored to limits of the quadrangle were covered by the Glance During the second eon, which may not have not decisive on this point. The most that can be their original nearly horizontal position and then conglomerate before any considerable part of the been sharply marked off from the preceding one, said is that there is apparent conformity between entirely removed, we should see exposed the old Morita beds was laid down, the land mass that fur­ this mountainous land was eroded. the Martin and Escabrosa limestones. The latter surface upon which they were laid down. In the nished the sands and muds must have lain 7 out­ It perhaps underwent many vicissitudes during formation, consisting chiefly of pure granular lime­ northern part of the quadrangle this surface would side of the area under investigation. The main this interval, involving oscillations in level and stone made,up very largely of the fragments of be a nearly level plain of erosion floored with shore line probably lay to the west of the Mule accumulations of fresh sediments which were only crinoids, records probably the deepest water that Pinal schist, granite, and granite-porphyry. In Mountains. ^~~ to be again stripped away by erosion. All that is ever covered the Bisbee region. So far as known the vicinity of the present Mule Gulch the plain After the greater part of the Morita sands and recorded, however, is a vast interval of erosion no land-derived sediments found their way into would terminate, and one standing upon its edge silts had accumulated in a sea that was apparently during which mountains were brought low and this part of the Mississippian sea. would overlook to the south a lower country diver­ poorly provided with animal life, there was a rocks bearing the stamp of deep-seated metamor- The most careful examination of many excel­ sified by hills of light-hued Paleozoic limestones. change in the character of the sediments. They phic processes were exposed at the surface of a lent natural sections has failed to discover any evi­ What geological events, it may be asked, resulted became more calcareous and gradually passed into nearly level plain of erosion. dence of unconformity between the Escabrosa and in this association of elevated plain and hilly the impure limestones, often crowded with marine 13 shells, that make up the lower member of the ECONOMIC GEOLOGY. 1 ores of copper. The unimportant deposit of lead copper is abundant as tough spongy aggregates of Mural limestone. These fossiliferous calcareous INTRODUCTION. carbonate in Hendricks Gulch, the first discovery small crystals, sometimes encrusting chalcocite and muds were in turn succeeded by the fairly pure in the district, is still worked in a small way, and sometimes enveloped in ferruginous clay or earthy limestone beds of the upper member of the Mural HISTORY OF MINING DEVELOPMENT. the Easter Sunday mine has supplied a siliceous oxide ores. It also occurs in thin layers along fis­ formation, indicative of a moderately deep sea Prior to 1880 Bisbee was an unimportant lead gold ore that is used in the Copper Queen smelter sures in clayey oxidized ground as small loose crys­ containing abundant animal life. The 650 feet camp, a single furnace being then in operation for converter lining, or ganister. But these, so tals up to 2 or 3 millimeters in diameter, which of Mural limestone, however, mark an episode upon the cerussite mined from the Hendricks claim, far as known, are the only ores in the quadrangle show the usual modified cubes and octahedra in a general accumulation of sands and silts, as is close to town. The copper ore of the Copper Queen that are commercially exploited for other metals embedded in a soft, earthy mixture of cuprite, shown by the return in the Cintura formation to mine was discovered early in this year, and was than copper. In comparison with the copper limonite, and kaolin. conditions of deposition similar to those which profitably exploited until 1884. This ore was free deposits the known occurrences of other ores are Pyrite. Although not, strictly speaking, an ore, prevailed during the laying down of the Morita from sulphur and averaged 23 per cent copper. It economically insignificant. pyrite is here included with the ore minerals on formation. was treated in two 36-inch furnaces, which, in For a district that has produced nearly 400,000,- account of its intimate chemical, physical, and The formations from the Glance to the Cintura spite of their small size and the use of wood as fuel, 000 pounds of copper, the Bisbee quadrangle, in genetic relationship to them. It is the most inclusive were deposited in the early Cretaceous were able to turn out about 500,000 pounds of spite of the general bareness of its rocky slopes, abundant and widespread sulphide in the district, (Comanche epoch), which accordingly is represented copper per month. In 1882 the men composing exhibits little superficial evidence of its mineral and the one of which all the ore bodies, however, by nearly 5000 feet of sediments. How much more the present Copper Queen Company bought the wealth. The porphyry mass of Sacramento Hill varied may be their present constitution, originally material was deposited during later Cretaceous and Atlanta claim, near the original discovery, and and the schists that partly inclose it southeast of in greater part consisted. Tertiary time is unknown. began prospecting. In 1884 the Copper Queen Bisbee show considerable alteration and contain In the form of small crystalline grains dissemin­ ore body, which had been worked for 300 feet abundant disseminated pyrite, which by oxidation ated through masses of altered rock, pyrite is abun­ POST-CRETACEOUS DEFORMATION AND EROSION. down an incline, was exhausted. The outlook was colors the rocks with a rusty stain, but so far as dant in the intrusive porphyry mass of Sacramento Since the deposition of the Cintura formation gloomy and work was almost abandoned when a known no deposits of value occur wholly within Hill and in the adjacent schists which partly the rocks of the quadrangle have been deformed second ore body was simultaneously discovered these rocks. Along the Dividend fault in Bisbee inclose that mass on the east. Associated with the by folding and faulting and subjected to erosion. from the original Copper Queen incline and from are outcrops of dark, rusty masses composed princi­ great bodies of copper ore disposed about the por­ The exact sequence of these events is not revealed. the Atlanta workings. In order to avoid legal pally of limonite. Similar ferruginous ledges phyry mass in the limestone south of Bisbee, pyrite The latest faults, for example, are certainly older complications the two companies combined as the occur in Hendricks Gulch, on Queen Hill, and in occurs in large quantity. In the upper levels of than much of the erosion, but the quadrangle Copper Queen Consolidated Mining Company, the limestone south of Bisbee. Experience has the mines, where oxidation has been aclive, it is may also have been actively eroded long before which gradually absorbed the neighboring proper­ shown that such limonitic croppings, although sometimes found in isolated masses inclosed in this faulting. ties by purchase. In 1886 the old smelting plant rarely containing appreciable quantities of cop­ envelopes of chalcocite and oxidized ore. In the The first event subsequent to Comanche sedi­ became inadequate and was rebuilt. Greater per-bearing minerals, are nevertheless frequently lower levels it forms extensive bodies which pass mentation recorded in the structure of the quad­ economy was necessary, as the average tenor of associated with an underlying ore body. They somewhat gradually into altered limestone in which rangle was a general tilting to the northeast at an the ore had fallen to about 8 per cent and the mark loci of fracturing and mineralization in the the pyrite occurs disseminated in small grains, angle of 15 or 20 degrees. This movement was price of copper had also notably declined. limestone. They evidently result from the oxida­ usually of rather irregular outline, and in little probably connected with regional elevation that Shortly after 1890 the completely oxidized ores tion of pyrite. The less soluble iron oxide and bunches and stringers. Of these pyritic bodies converted the sea bottom of early Cretaceous, time showed signs of failing, but in 1893 the works were some silica remain near the surface, while such cop­ only those portions that contain chalcopyrite or into dry land. The northeasterly tilting, which remodeled by the introduction of converters, and per as was originally present has .been carried down chalcocite have proved workable. appears to have affected the whole of the Mule sulphide and oxide ores have since that time been by percolating solutions and redeposited at lower Microscopical examination of thin sections shows Mountain mass, may have resulted from a gentle successfully worked together by the matte process. levels. These bodies of limonite, when not too that the pyrite disseminated through the limestone anticlinal arching of the Cretaceous beds and their The introduction of these converters was due to Dr. siliceous, are the best surface indication of ore that is nearly always associated with tremolite, diopside, underlying Paleozoic and pre-Paleozoic basement. James Douglas and marked the beginning of a new the district affords, although it by no means follows garnet, or vesuvianite. In some cases the calcite If so the Mule Mountains are part of the northeast epoch in the smelting of copper ores in Arizona. that there is always ore beneath them. Many of of the limestone has been entirely replaced by sili­ limb of a broad anticline whose southwestern limb Up to the end of 1902 practically all the copper the most important ore bodies, on the other hand, cates and pyrite, with usually more or less quartz; must have extended over the region now occupied from Bisbee was the product of the connected group would have remained undiscovered were superficial in other cases, the silicates are lacking and the by the San Pedro Valley and has been either down- of mines owned by the Copper Queen Company. phenomena alone relied upon to suggest explora­ limestone has been altered to a mass of quartz and faulted or cut away by erosion. Another possible Recently, however, extensive ore bodies have been tion. Although the rocks of the quadrangle are pyrite. The pyrite is contemporaneous with these explanation is that the Mule Mountains constitute opened up in the Calumet and Arizona mine, and seamed with faults and dikes none of the workable minerals, and is intergrown with them. a tilted fault block whose weathered escarpment in the latter part of December, 1902, this company copper deposits occur as lodes or fissure veins. Chalcopyrite. So far as observed, in the Bisbee overlooks the downthrown tract of San Pedro was turning out from 30 to 40 tons of copper a With a few exceptions they a,re irregular replace­ quadrangle this mineral occurs only in massive Valley. The verification of either of these princi­ day from its new smelter at Douglas. ments of limestone. Originally pyritic, containing form, never in distinct crystals. It is apparently pal hypotheses involves, however, more than the probably subordinate amounts of chalcopyrite, they confined to the limestones. Unlike the pyrite it is MINES. study of a single quadrangle. From the fact that owe their present value to secondary concentrations rarely found in a disseminated condition, but the Cretaceous beds of the Bisbee quadrangle exhibit The Bisbee quadrangle contains two large pro­ effected by processes of sulphide enrichment and when present at all is likely to be accompanied by minor northwest-southeast folds, the hypothesis that ductive copper mines the Copper Queen and the oxidation. pyrite and to constitute fairly solid masses of ore. the post-Cretaceous northeasterly tilting is a result Calumet and Arizona. The former comprises a An excellent example of such an occurrence may DISTRIBUTION OF THE ORE BODIES. of a broad anticlinal structure is for the present maze of workings connecting with the surface be seen in a body of chalcopyrite ore on the seventh regarded as having the greater probability. through the Czar, Holbrook, Spray, and Gardner The principal bodies of copper ore thus far level of the Spray mine. As an ore-forming min­ As a result of this differential elevation the beds shafts. The area exploited covers nearly half a exploited in the quadrangle are contained within eral, however, it is much less common in the pres­ of the Bisbee group stood highest in the southwest­ square mile, while the vertical range of exploration an irregular area that is approximately a quarter of ent workings of the Bisbee mines than chalcocite ern part of the quadrangle. With the progress of is about 950 feet. The Calumet and Arizona mine a square mile in extent. This area begins at the and the various oxidized ores. erosion these upraised beds were first carried away adjoins the Copper Queen on the south and is north in the heart of the town of Bisbee and Sphalerite. Sphalerite, or zinc blende, is of rare and more and more of the pre-Cretaceous basement worked through the Mag shaft, 1200 feet in depth. extends southward for three quarters of a mile. It occurrence in the Bisbee quadrangle. It occurs was exposed, until at the present day the Creta­ Other mines which were being operated in 1902, lies west and northwest of Sacramento Hill and occasionally in little specks, with pyrite and chal­ ceous beds have been stripped from the greater part and which, although not then productive, contain for the most part between the Czar and Calumet copyrite, in metamorphic limestone. of the southwestern half of the quadrangular area. some copper ore, are the Lowell, 1120 feet deep, and Arizona (Irish Mag) shafts. Chalcocite. This mineral, familiarly known as This denudation, however, has not gone on without and the Cole shaft of the Lake Superior and Pitts- Outside of this limited area, no large bodies of copper glance or "glance," is the most important interruption. At some stage during its progress burg Company, about 1000 feet in depth. The copper ore have yet been discovered, although sulphide occurring in the Bisbee quadrangle, since occurred post-Cretaceous faulting of two distinct Calumet and Pittsburg, 950 feet deep, the Bisbee more or less ore is known to occur in the Lowell, nearly all of the bodies of workable sulphide ore kinds normal faults of moderate throw, exempli­ West mine, 700 feet deep, and Glance mine, 500 Uncle Sam, Whitetail, Wade Hampton, and other owe their value to its presence. So far as observed fied by the Mexican Canyon fault, and extensive feet deep, are active prospects which up to the mines and prospects. it occurs only in massive form, distinct crystals overthrusts produced by forces operating along close of the year 1902 had not found ore in paying being nowhere seen. It is sometimes firm, and MINERALOGY OF THE ORES. nearly east-west lines and resulting in the struc­ quantities. The Easter Sunday, although a small compact in texture, but is often rather soft, and ture of the Gold Hill and Glance blocks. mine, is of exceptional interest as the only pro­ ORE MINERALS. occasionally has almost a sooty character. Much During late Cretaceous and Tertiary time the ducer of gold ore in the quadrangle. Native copper. Copper in the native state was of the sulphide ore occurs as friable, granular Bisbee quadrangle was probably a land area under­ not an uncommon constituent of the lower portions pyrite, each grain being coated with chalcocite. PRODUCTION. going erosion. No formations referable to these of the great oxidized ore bodies that were worked a In the Copper Queen group of mines, chalcocite periods are known within the quadrangle. It is The total production of the Copper Queen mine few years ago in the Copper Queen mine. Accord­ is found at various depths but never far from oxi­ possible that some of the unconsolidated material from the beginning of operations to the end of ing to Dr. Douglas it was abundant just above the dized ore. Its most characteristic place of occur­ penetrated by deep wells in Sulphur Spring Val­ 1902 was about 378,047,210 pounds of copper. third level at the bottom of the great ore body rence is in the irregular zones of rich sulphide ore ley may be Tertiary, but there is as yet no evi­ If 2,000,000 pounds be added to the above total southwest of the Czar shaft, where it occurred some­ tKat usually intervene between masses of lean dence justifying the separating of these deposits as the roughly estimated product of mines other times in masses weighing several hundred pounds. pyrite and oxidized ores containing cuprite, native from the overlying Quaternary accumulations. than those of the Copper Queen group there is Native copper is now, however, rather rare in this copper and carbonates. obtained a total output for the Bisbee quadrangle, to mine, but is abundant in the Calumet and Arizona In the Calumet and Arizona mine chalcocite is QUATERNARY EROSION AND DEPOSITION. the close of 1902, of 380,047,210 pounds of copper. mine, particularly on the 950- and 1050-foot levels. found associated with cuprite, limonite, malachite, The record of Quaternary time is one of unin­ It is usually closely associated with cuprite and and brochantite (a basic sulphate of copper). As COPPER ORES. terrupted erosion. During this period the pres­ occurs as a rule in proximity to sulphide ores. On in the Copper Queen mine, it frequently occurs as GENERAL CHARACTER OF MINERALIZATION. ent topography was carved. - Under the more the 950-foot level, about 400 feet southeast of the a dull, cryptocrystalline coating on pyrite. humid conditions that probably prevailed/ in the The Bisbee quadrangle owes its economic impor­ shaft, the bulk of the ore of a large rich stope In the Lowell mine, chalcocite occurs in a soft, Pleistocene epoch, much of the material stripped tance exclusively to the occurrence within it of consists of crystalline cuprite bound together into black earthy condition, with partly oxidized pyrite, from the Mule Mountains was carried down to the a tough mass by an irregular web of native cop­ and also in a more compact form associated with 1 For a fuller account of the Bisbee ore deposits than can sea. But with the increasing dessication of later be compassed in the brief outline of a folio text, from which per. With the cuprite and copper are associate^ pyrite, native copper, and malachite. Pleistocene and Recent time the bulk of the detritus details and discussion are purposely excluded, the reader is some limonite and other earthy oxides and a little Outside of the larger mines chalcocite is found referred to a report on the geology and ore deposits of the fibrous malachite, chiefly in vugs. irregularly but widely distributed through the large has accumulated in the neighboring Sulphur Spring Bisbee quadrangle, published as Professional Paper No. 21 and San Pedro valleys. of this Survey. On the 1050-foot level of this mine, native area of Glance conglomerate that stretches from Bisbee. 14

Gold Hill southward to the international boun­ 850-foot level of the Calumet and Arizona mine. ene, garnet, chlorite, quartz, vesuvianite, and other or the feldspars of the granite-porphyry. Small dary. The mineral occurs in minute reticulating It occurs as thin shells about nuclei consisting of minerals. amounts of quartz may usually be found as a micro­ veinlets, often microscopic in size, and in little crystalline cuprite, native copper, and brochantite. In the form of stalactites, often beautifully col­ scopic constituent, associated with tremolite, diop­ rounded bunches, rarely over half an inch in diam­ Aurichalcite. This mineral, a basic carbonate ored with salts of copper, and in showy crystalline side, garnet, and pyrite, of the altered limestones of eter, usually inclosed within a thin envelope of of zinc and copper, has been reported from the masses, calcite was abundant in the bodies of oxi­ the locally prevalent type. Near the porphyry malachite. The chalcocite is usually accompanied Copper Queen mine, but none was seen in 1902. dized ore worked in early days in the Copper mass of Sacramento Hill quartz is more abundant by the development of a secondary quartz in vein- Brochantite. This green, orthorhombic, basic Queen mine, and is still encountered to some than elsewhere. Much of the rock in the vicinity lets and small vugs. Both chalcocite and quartz sulphate of copper is not abundant in the Bisbee extent within the oxidized zones. It is rarely, of the Gardner shaft, for example, originally lime­ have in part filled minute fissures in the conglom­ quadrangle, but has been noted in small amounts, however, a conspicuous gangue mineral in the ores stone, now consists essentially of a finely crystalline erate, but have also in part replaced some of the often associated with malachite, for which, upon now exploited. granular aggregate of quartz with varying amounts finer interstitial calcareous matrix by which the superficial examination, it might readily be mis­ The unoxidized pyritic ores, particularly those of pyrite and chlorite. The bottom of the shaft, pebbles are held together. taken. too poor for working, are intimately associated with in 1902, was in such material. Quartz of the same The mass of conglomerate forming the hill just As a rule it is recognizable in the Bisbee ores several minerals, chiefly silicates of calcium, mag­ fine-grained granular character, associated with west of the Glance mine exhibits well the scattered only by the microscopical examination of thin sec­ nesium, and aluminum in varying proportions, pyrite, sericite, and kaolin, also makes up much of mineralization just described. The occurrence of tions. Its most characteristic occurrence is in the which so far as observed occur only in crystals the altered and mineralized granite-porphyry of this chalcocite in the Glance conglomerate has led form of little nests and irregular veinlets in the of microscopic size. Their identification accord­ Sacramento Hill. to extensive prospecting, which has not, however, cuprite of the Copper Queen and Calumet and ingly depends upon the microscopical investigation Most of the soft, earthy oxidized ores mined in the revealed workable ore bodies. Arizona mines. of thin sections. Of these probably the most com­ Copper Queen and the Calumet and Arizona mines About 1000 feet northwest of the No. 3 shaft of Brochantite is not sufficiently abundant to form mon is the calcium-magnesium amphibole tremolite, are accompanied by and more or less intimately the Lake Superior and Pittsburg Company chalco­ an important constituent of the Bisbee ores, and its usually occurring in aggregates of minute radiating mingled with limonite and clays of various colors. cite altering to malachite occurs in a little vein in occurrence in the district has not been previously prisms, which under the microscope show the char­ The limonite sometimes occurs in stalactitic or Martin limestone. This is the only observed recorded. acteristic cross sections, cleavage, and optical prop­ botryoidal form, but in the present workings is instance in the quadrangle of the occurrence of Cuprite. The red oxide of copper is an abun­ erties of this mineral. Nearly or quite as abundant, more often earthy, and mixed with ore or clay. the mineral in a fissure vein. dant and important constituent of the Bisbee ore and usually accompanying the trcmolite, is a color­ The clay is sometimes white, sometimes pink or Malachite. The familiar green carbonate of cop­ bodies. It occurs sometimes in an impure earthy less pyroxene which occurs in microscopic grains, greenish-gray, but more often it is yellow or red­ per is found in greater or less quantity wherever condition, mixed with limonite and ferruginous as a rule less than a tenth of a millimeter in diam­ dish, from the presence of limonite. A snow-white, copper ores are undergoing oxidation. In the clays; sometimes in crystalline masses, associated eter, rarely showing sharp crystal outlines, but waxy variety, beautifully diversified by little vein- older workings of the Copper Queen mine this with native copper. The latter occurrence is par­ exhibiting a distinct tendency to the development lets of light-green malachite, was collected on the mineral was abundant, occurring in large and ticularly characteristic of the deeper oxidized zones of stout prismatic form. This mineral has the second level of the Copper Queen mine, about 250 beautiful masses with azurite and calcite in caves in the vicinity of chalcocite and other sulphides. optical properties of diopside. Although neither feet south of the Holbrook shaft, and was subjected in the limestone. The walls of these caverns were In the present workings of the Copper Queen tremolite nor diopside, so far as observed, occur in to chemical examination as representative of the covered with velvety moss-green malachite and mine the bulk of the cuprite occurs in the earthy the Bisbee quadrangle in crystals large enough to purest form in which these clay-like secondary sparkled with the blue crystals of azurite, while condition, mixed with limonite, pure crystalline be seen with the naked eye, their presence in the products occur. According to Dr. W. F. Hille- from the roofs hung translucent stalactitic dra­ masses of any size being comparatively rare. In altered mineralized limestone can generally be brand the material contains no carbon dioxide and peries of calcite, delicately banded and tinted with the Calumet and Arizona mine, however, new recognized by a faint greenish tint in the rock, no magnesia. It suffers a loss of 22.8 per cent of the salts of copper. But the caves have been stopes have been opened in ore bodies contain­ joined with a certain compactness of texture unlike silica on ignition, and the residue consists chiefly stripped of their treasures and either filled with ing cuprite in large crystalline masses, usually that found in any of the unaltered limestones. of silica and alumina. It is thus probably nearly waste or allowed to collapse. They are things associated with native copper, and in beautiful Most of the limestone encountered in the Spray pure Icaolinite, although too minutely crystalline to of the past, and museum specimens, of which per­ druses of ruby-red isometric crystals, usually in workings from the fourth level down, and in the reveal any distinct structure under the microscope. haps the finest collection is that in the American the form of simple cubes or of cubes modified by Calumet and Arizona mine from the 850-foot level This white kaolinite, which occurs in bunches and Museum of Natural History in New York, can the octahedron and dodecahedron. down, exhibits this development of tremolite and streaks in earthy limonite and ore, is usually asso­ but feebly suggest their former splendor. Tenorite. The crystalline form of the black diopside, and all gradations may be studied, from ciated with bright-red and pale-green varieties, the The malachite occurred in the form of mammil- oxide of copper was not observed in the course of limestones consisting almost exclusively of calcium former owing its color to oxide of iron and the lary incrustations, which, while often of consider­ the present investigation. The earthy variety, carbonate to those in which all of the carbonic latter to some salt of copper. able thickness, were of fibrous texture and not however, commonly known as melaconite, occurs anhydride has been replaced by silica. These clays, in varying purity, together with soft adapted to the ornamental purposes to which the in some of the soft, clayey ores, usually mixed A colorless garnet, probably the calcium-alumi­ earthy limonite, constitute the most abundant and well-known Russian malachite has long been with the black oxide of manganese in the form of num garnet grossularite, occurs in some of the characteristic gangue materials of the thoroughly applied. a light, sooty powder. Ore of this character con­ altered limestone associated with tremolite and oxidized ores. In the present workings of the Copper Queen taining about 5 per cent of copper was observed in diopside. As seen under the microscope in thin PAR AGENESIS OP THE ORE AND GANGUE MINERALS. mine, malachite is not very abundant. It occurs the Lowell mine. In the Calumet and Arizona section, it occurs in imperfect crystals of rounded usually in little nests and bunches in soft limonitic mine, about 800 feet below the surface, there is outline, often poikilitically inclosing other con­ By paragenesis is meant the association of the ore containing earthy cuprite. The presence of in the limestone a natural cavern whose damp stituents of the rock. It is seldom perfectly iso- various ore and gangue minerals with special refer­ little green specks of malachite in such ores is gen­ walls are covered with a black, moss-like botryoidal tropic but usually exhibits an indistinct and irregu­ ence to the order and mode of their formation. It erally indicative of a high tenor in copper. growth. This material is apparently still being lar birefringence a not uncommon phenomenon is not, however, implied in the definition that the The Calumet and Arizona mine exhibits similar deposited, for the fragile stems of the dendritic for grossularite. This mineral, associated with minerals were formed in any rigid, unalterable occurrences, but the mineral is here found also in efflorescence break off" by their own weight when tremolite, diopside, and calcite, was particularly sequence or that the development of any one vugs within masses of crystalline cuprite and native they reach a length of over half an inch and the noted in the altered limestone from the new station mineral was a synchronous process in different ore copper. floor of the cavern is deeply covered with a fluffy on the 1150-foot level of the Calumet and Arizona bodies, or was peculiar to any particular division of In both the Copper Queen and Calumet and carpet of this black material. Inspection of the mine (the deepest point reached in the under­ geological time. Arizona mines the malachite is frequently associ­ walls shows that this is composed of alternating, ground exploration of the district) and on the fifth Among the metallic sulphides of the Bisbee ated with small amounts of brochantite, a mineral irregularly overlapping layers of the black efflores­ level of the Holbrook, northeast of the shaft. It is copper deposits, pyrite was undoubtedly one of easily mistaken for the green carbonate, and with cence with druses of calcite. Chemical tests of the probably fairly abundant throughout the compact, the first to form. Whether small quantities of chrysocolla. Nowhere at the present time does it black material show that it is a mixture of the greenish, pyritized limestones in the deeper levesl chalcopyrite and minute amounts of sphalerite were constitute more than a very small portion of the oxides of copper and manganese, probably melac­ of the Copper Queen, Calumet and Arizona, and deposited at the same time as the primary pyrite, ore. onite and bog-manganese, or wad. Lowell mines. is a moot question. Although some of the chalco­ Azurite. The blue carbonate of copper, while Koenig, in 1891, described some small black In several thin sections of the altered limestones pyrite is certainly later than the bulk of the pyrite, formerly fairly abundant and occurring in large crystals from the Copper Queen mine and con­ from the Copper Queen and Calumet mines there yet the contemporaneous formation with the latter crystalline slabs in the oxidized ores in the Copper cluded that they were essentially a mixture of was noticed, in addition to the minerals already of more or less disseminated chalcopyrite is by no Queen mine, is now seldom found, except in cupric and cuprous oxides and were tetragonal in enumerated, small colorless prisms, having an index means disproved or improbable. The association occasional little bunches in the earthy ferruginous crystal form. He decided that they represented of refraction about equal to garnet but with a bire­ of most of the pyrite with amphibole, pyroxene, ores of the thoroughly oxidized zones. a distinct mineral species, for which he proposed fringence somewhat lower than quartz. The few garnet, and vesuvianite is such as to demonstrate Chrysocolla. The hydrous silicate of copper, like the name paramelaconite. cross sections found are square or octagonal and their essentially contemporaneous development in malachite, azurite, and brochantite, is a minor con­ Footeite. This mineral, a deep blue chlor- remain dark between crossed nicols. The mineral the limestone. To the same general epoch of min­ stituent of the Bisbee copper ores, and seems never hydrate of copper, occurring in minute monoclinic extinguishes parallel with the prism, and the pris­ eralization belongs also the formation of most of to have been very abundant. It was noted in the prisms implanted with paramelaconite on limonite, matic axis corresponds with the direction of greatest the quartz and chlorite associated with the ores. Calumet and Arizona mine, where it forms thin was first described and named by Koenig, from a elasticity. The mineral is probably vesuvianite, a In the development of the ore and gangue min­ concentric shells about kernels of crystalline specimen said to have come from the Copper basic calcium-aluminum silicate of somewhat uncer­ erals, there is thus distinguishable an early stage cuprite, native copper, and brochantite, and is Queen mine. Footeite is evidently of rare occur­ tain formula. characterized by the practically simultaneous appear­ enveloped in turn by malachite and calcite. Inti­ rence in the Bisbee mines and was not seen in The metasilicate of calcium, wollastonite, was ance of pyrite, tremolite, diopside, grossularite, mately associated with the chrysocolla is a lustrous, 1902. looked for in the altered limestones but was not vesuvianite, chlorite, quartz, and perhaps also of brittle, pitch-black substance which Koenig has detected in any of the thin sections, although the chalcopyrite and sphalerite. GANGUE MINERALS. recently described as a new mineral species and silicates described are those with which it is often That at least some of the chalcopyrite is of more named melanoehalcite. Of the various minerals associated with the ores, associated. recent origin than pyrite is shown by the occurrence Melanoehalcite. This is described by Koenlg as calcite, in its role of principal constituent of the Quartz varies greatly in abundance in different of chalcopyrite as an envelope about grains of pyrite forming a thin envelope about kernels of cuprite limestone in which the important ore bodies occur, portions of the ore-bearing ground. A few small and as veinlets in the latter mineral. and inclosed in turn by chrysocolla. It is black, is the most abundant. It is seldom, however, that veinlets of quartz, carrying pyrite, were observed Such sphalerite as was observed in the Bisbee with a pitchy luster, and apparently amorphous. the mineral forms so large a part of the altered in the altered limestone on the 950-foot level of quadrangle was always closely associated with chal­ According to Koenig's chemical analyses, it is limestone in the immediate vicinity of the ore as it the Calumet and Arizona mine, but vein quartz is copyrite and was probably formed at the same time a silico-carbonate of copper having the formula does of the unchanged rock in which mineraliza­ exceptional in connection with the cupriferous ore as the latter mineral. Cu 3 (8iC)0 4 .Cu(OH) 2 . tion has not been active. As will presently be bodies. The mineral, where it occurs at all, usually Chalcocite is undoubtedly the most recently Material identical with that described by Koenig shown, it has been largely, in the process of min­ has the form of fine-grained aggregates that have formed sulphide mineral occurring in the' Bisbee was obtained from the same locality, namely, the eralization, replaced by pyrite, amphibole, pyrox­ replaced the calcium carbonate of the limestone ore bodies, and has resulted from the action upon other sulphides, chiefly pyrite, of solutions mov­ of the ore is very much obscured by metamor- side of the Czar fault to the Czar shaft, thence Dividend fault. On the surface the contact is ing generally downward from the zone of oxida­ phism, if it is not entirely obliterated by the southeastward along the southwest side of the Divi­ concealed by superficial material in the gulch that tion. extensive formation of ferruginous clay resulting dend fault to the contact with the Sacramento Hill comes down from the Spray shaft past the hospital. Of the minerals of the oxidized zone cuprite and from the oxidation and decomposition of the ores porphyry near the hospital. Here the ore belt Even on the western slope of Sacramento Hill, native copper are apparently among the first to and country rock. Furthermore, the ore some­ swings to the south, skirting the porphyry mass where the rocks are well exposed, the porphyry and develop, since they occur usually near the bottom times cuts across the bedding of the limestones toward the Spray and the Calumet and Arizona limestone are so much altered that the actual con­ of the oxidized ore, in proximity to the sulphides. for considerable distances, as will be shown later. shafts. Whether it continues to skirt the por­ tact between the two is rather indefinite. Under­ The direct alteration of chalcocite into native copper Owing to the extensive alteration of the lime­ phyry to the east, past the Gardner and Lowell ground crosscuts have not been driven far enough is exhibited by specimens from the Calumet and stones in the vicinity of the ore bodies, observations shafts, toward the ice factory and Mule Gulch, to throw much light on the details of the rela­ Arizona mine. These show very irregular kernels on dip and strike of the beds can be made in but a is yet to be proved by underground work. tion between porphyry and ore. They have of compact chalcocite encrusted with a spongy small part of the extensive underground workings The Czar fault is a well-established but remark­ usually been stopped whenever anything supposed aggregate of small, sparkling crystals of native of the Copper Queen mine. Such observations as ably inconspicuous normal dislocation, with an to be porphyry appeared at the face. copper, associated with a little earthy cuprite. The were recorded indicate a general southeasterly dip estimated downthrow of about 500 feet to the The general conclusion drawn from such meager copper is not strictly confined to the exterior of the of less than 20 degrees, but there is much diversity, southeast. The surface phenomena connected data as are obtainable in regard to the contact chalcocite kernels but penetrates. these for varying and the beds were evidently subjected to consider­ with it are described on page 9. The identifica­ between the Sacramento Hill porphyry and the distances up to about half an inch in the form of able local disturbance prior to the deposition of the tion of the fault in the underground workings is limestones may be given in a few words. The little vugs and indefinite stringers. ore. At the old Queen incline, which follows the by no means satisfactory, owing to the prevalent contact is very imperfectly explored. It is appar­ As a rule cuprite has formed just after the native bedding, the dip is about 40 degrees and is toward decomposition of the disturbed and altered lime­ ently irregular, with conspicuous departures from a copper with which it is immediately associated, but the south. This steep and unusual local dip stone to the soft, ferruginous, clayey material simple curved surface. It is the locus of pro­ the sequence is by no means always clearly shown. apparently accounts for the exceptional attitude of known as "ledge matter." In general the fault nounced metamorphism and mineralization which In the Calumet and Arizona mine native copper the original Queen ore body> a roughly cylindrical seems to separate extensive areas of this "ledge- extend both into the limestones and into the por­ occurs in branching crystalline masses beautifully mass 60 feet in diameter and 400 feet in length, matter," containing large ore bodies and extending phyry. Pyrite occurs in great abundance in the encrusted with crystals of cuprite. The cuprite is inclined at an angle of 30 or 40 degrees from the eastward toward the Holbrook shaft, from harder, immediate vicinity of the contact, characteristically in such cases obviously the younger mineral. At horizon. less mineralized limestones on the northwest, in in disseminated form but occasionally in consider­ other places in the same mine the two minerals This single ore body, according to Douglas, which no important ore bodies have yet been able masses. The workable bodies of ore, owing are found so intimately associated that it is difficult yielded about 80,000 tons of ore and 20,000,000 found on this level. It is probable, although by their value to enrichment that took place subse­ to determine which was the first to form. The pounds of copper. no means certain, that the "ledge matter" on the quent to the primary pyritic mineralization, occur copper constitutes a metallic mesh or sponge which Between the Queen incline and.the Holbrook southeast of the supposed fault line is altered and within the mass of the limestones, usually at some is filled with crystalline cuprite. Although some shaft and southwest of the Czar shaft the usual decomposed Escabrosa limestone, and that the distance from the actual contact to whose curved of the copper may have formed slightly in advance gentle southeasterly dip seems on the whole to pre­ harder limestone on the northwest is Martin or course their distribution in the main conforms. of some of the cuprite, both minerals were probably vail, although opportunities for satisfactory obser­ perhaps, in part, Abrigo limestone. It is highly probable, if not reasonably certain, crystallizing at the same time. vation are rare. The ~ very important ore bodies It was probably in consequence of the Czar fault that other fissures than the Czar and Dividend Brochantite has been found only in close associ­ occurring in this part of the Copper Queen mine that so much difficulty was encountered in finding faults have helped to determine the form and posi­ ation with cuprite and appears to have been formed have been found on the whole to be nearly hori­ new ore bodies after the exhaustion of the original tion of individual ore bodies. Such fissures, how­ shortly after that mineral. Melanochalcite and zontal. As a rule very few traces of original bed­ Queen stope. The great cylindrical ore mass was ever, can not be satisfactorily studied in mines chrysocolla are also characteristic of the deeper por­ ding are discoverable in the much altered, mineral­ on the northwest side of the Czar fault, while the where ore values and extensive oxidation are so tion of the oxidized zone. The sequence of forma­ ized, and decomposed material occurring within bodies afterwards discovered at lower levels have closely related and where workings in the soft, tion as shown in specimens from the Calumet and 500 feet of the probable position of the Dividend been in the downthrown southeast block. clayey ground soon close upon disuse. In the Arizona mine was: native copper, cuprite, . broch- fault. The detailed relations of the ore bodies of the Lowell mine there is abundant evidence that ore antite, melanochalcite, chrysocolla, malachite, and In the Spray workings the general dip of the Copper Queen mine to the Dividend fault are very deposition was facilitated by irregular fissuring of calcite. limestones appears to be toward the southeast at obscure. Large bodies of ore have been mined general north-south trend. Most of the disturb­ In general the formation of limonite appears an angle of about 15 degrees. The ore bodies cor­ and are still being worked in the vicinity of this ance appears to have consisted of differential move­ to have accompanied or closely followed that of respond roughly to this gentle inclination. great fissure,, but the ground is soft and openings ments along planes of bedding (bedding faults), cuprite and to have continued for some time after, In the Calumet and Arizona mine the limestones in it are very difficult to maintain. Such cross­ though occasional irregular fractures of no great so that it is also intimately associated with the maintain their general southeasterly dip, but are cuts as have been run to the northeastward, beyond vertical persistency cut across the beds. occurrence of malachite and azurite. on the whole more steeply inclined than in the the ore bodies, are no longer accessible, and it is RELATIONS TO THE ESCABROSA LIMESTONE. The azurite on the whole belongs to a later stage adjoining Copper Queen workings, the average dip not known whether any of them penetrate the of the general oxidation than the malachite. But being about 35 degrees. Stoping had not gone far schist which, at the surface, forms the country Although the ore bodies as a rule have their there is much overlapping in the occurrence of enough in 1902 to demonstrate the approximate rock northeast of the fissure. The ore bodies in greater dimensions in the planes of bedding they these two carbonates. shape of the large ore bodies. There is little this part of the mine were apparently formed for the are not confined to any particular bed or to any Tenorite is usually associated with wad, or "bog doubt, however, but that they are of the same gen­ most part in limestone, but the mineralization and definite stratigraphic horizon. The original Queen manganese," in the upper part of the zone of oxi­ eral character as those worked from the Spray subsequent alteration has been so intense that very ore body occurred in the lower part of the Esca­ dation. shaft, although more noticeably inclined in con­ little of the original country rock can now be iden­ brosa limestone. The ore in the Baxter tunnel, formity to the increased dip of the inclosing beds. tified. Masses of earthy oxidized ore and bodies near the Holbrook shaft, occurs in part in the MODE OF OCCUEKENCE OF THE ORES. The development of the Lowell mine is as yet of crumbling pyrite, more or less enriched with lower part of the Naco limestone. In the latter FORM AND DIMENSIONS OF THE ORE BODIES. insufficient to throw much light on the shape and chalcocite, occur very irregularly amid abundant, formation also occurs probably a portion of the ore The Bisbee copper ores, as exploited in the Cop­ extent of the ore bodies. They are evidently of soft, clayey, and limonitic material. The general in the Calumet and Arizona mine, and almost cer­ per Queen, Calumet and Arizona, and Lowell mines, irregular form, but lie with their two greater parallelism of the ore bodies with the bedding tainly that so far discovered in the Lowell mine. occur for the most part very irregularly as large dimensions parallel to the bedding planes of the planes of the limestone, elsewhere in these mines The problem of determining the stratigraphic hori­ masses in the Escabrosa and Naco limestones. The limestone, which here have an easterly dip of from a noticeable feature, is much less distinctly shown zon at which most of the great ore bodies of the horizontal dimensions of these ore bodies are usually 35 to 45 degrees. These ore bodies are undoubt­ in those workings that are regarded as being near Copper Queen and the Calumet and Arizona mines much greater than the vertical. They are rudely edly of the same general type as those found in the the Dividend fault. occur is a difficult one. Not readily distinguish^ tabular or lenticular in form, and lie generally Copper Queen and Calumet'and Arizona mines. In that very productive part of the Copper able over the quadrangle at large, the Naco and parallel to the bedding planes of the inclosing Queen workings lying northeast of the Holbrook Escabrosa limestones can not be separately identified RELATIONS TO STRUCTURES OTHER THAN BEDDING. limestones. Definite walls are exceptional. As a shaft, and in the corner formed by the Dividend in the mines, where metamorphism has altered the rule the oxidized ore passes gradually and irregu­ Bedding planes are not the only elements of fault and the contact of the limestones with the original texture and composition, obscure'd much larly on its peripheries into so-called "ledge matter," geological structure that have influenced the depo­ porphyry of Sacramento Hill, minor intrusions of of the structure, obliterated all of the fossils, and consisting chiefly of soft limonitic clays, which in sition of ore. In the deeper workings of the prin­ porphyry, probably apophyses or offshoots from transformed both limestones to similar aggregates turn grade into more or less altered limestone. The cipal mines, particularly of the Calumet and the main intrusive stock, have influenced the of silicates and pyrite. When upon such meta­ unoxidized sulphide ores may exhibit a peripheral Arizona, there is a well-marked and significant deposition of the ore to an extent recognized by morphism there is further imposed widespread transition either to oxidized ores or to metamor­ tendency of the original pyritic impregnations to the miners, who expect to find ore bodies in con­ alterations into limonitic clays and oxidized ore, phosed limestone impregnated with pyrite. concentrate along minor zones of fissuring and tact with them. - They appear to have the form the possibility of distinction between the two orig­ On any single horizontal plane the dimensions shearing in the generally mineralized limestone. of irregular dikes or, occasionally, sills. They are inal limestones vanishes. Structural relations (see of the ore masses rarely exceed 150 by 200 feet, That tendency, clearly shown on a small scale sometimes impregnated with a little pyrite and are structure sections) render it very probable that the but series of connected stopes indicate that in usually below and at a little distance from the often decomposed to a white or yellow clay, which great ore-bearing member of the Paleozoic series is general plan these figures may be considerably main ore bodies, is not merely a minor phenom­ usually reveals its origin by the presence of grains the Mississippian or Escabrosa limestone, which exceeded. Thus the stopes northeast of the Hoi- enon, but illustrates in miniature what has taken of quartz representing former phenocrysts in the has a thickness of about 700 feet. More exact and brook shaft in the Copper Queen mine indicate the place on a much larger scale in connection with porphyry. assured conclusions might be drawn from gen­ existence of a practically continuous body of ore the gr-eat ore masses. In the case of the latter, The presence of the porphyry dikes and sills in eral structural relations as interpreted in the struc­ and "ledge matter" about 800 feet in length and however, the important part played by fissures in the limestones, while by no means a necessary con­ ture sections were there less local disturbance in the 600 feet in width. On the other hand, the actual ore deposition is to a considerable extent obliter­ dition to the formation of ore bodies, is yet favor­ beds, were the presence and effect of faults in the maximum thickness of the ore bodies hitherto ated by later changes wrought in ore and country able to their occurrence. The function of these limestones more readily determinable, and did extensively worked rarely exceeds" 125 feet. rock by general oxidation and secondary concen­ minor porphyry intrusions with reference to ore the underground workings afford some direct check trations. The horizontal distribution of the impor­ deposition appears to have been similar to that of on the deeper structure as projected from studies RELATIONS TO THE BEDDING OF THE LIMESTONES. tant ore bodies is related to certain structures that fissures in influencing the movements of the min­ on the surface. The probability, however, is strong The statement that these very irregular tabular are nearly vertical. These are the Czar and Divi­ eral-bearing solutions in their circulation through that the Escabrosa limestone, while not the only or lenticular masses of ore lie parallel with the dend faults and the main limestone-porphyry con­ the limestones. ore-bearing formation, is the one that contains bedding planes of the inclosing limestones is the tact. The ore bodies on the whole constitute a That there is a genetic connection between the most of the great known ore bodies in the Copper simplest expression of a general relation and broad belt, about 900 feet in width, which begin­ porphyry mass of Sacramento Hill and the deposi­ Queen and the Calumet and Arizona mines. requires some qualification when the ore bodies ning (so far as present explorations show) at a tion of the ores is certain. The actual relation of Facts lending some additional support to this are studied in detail. It is then found that the point about 2000 feet southwest of the Czar shaft, the ore bodies to the porphyry-limestone contact is, hypothesis are (1) the known occurrence of the original structure of the limestone in the vicinity continues northeastward, chiefly along the southeast however, nearly as obscure as in the case of the original Queen ore body in the Escabrosa lime- Bisbee. 16 stone; (2) the greater depth at which other ore that have resulted wholly from the primary meta­ exposed on the surface is thus a siliceous mass con­ in the vicinty of Sacramento Hill was the result of bodies were subsequently discovered southeast of somatic mineralization, while not denied, is still as taining nests of kaolin, which sometimes weather out, extensive metasomatic metamorphism in some way the Queen incline, suggesting that they were formed far from proof as when Dr. Douglas published his leaving empty cavities. It is superficially stained due to the coincident occurrence of limestones, a in the same limestone as the Queen ore body but excellent account of the Copper Queen mine three and streaked with oxide of iron, but is generally considerable intrusive mass of porphyry, and prom­ occur at a lower level because that limestone had years ago. nearly white on freshly fractured surfaces. inent fissures extending to great depth. been dropped prior to the general mineralization The alteration of the Final schist in the vicinity The objection to regarding the metamorphism by the Czar fault; and (3) the progressively greater PRIMARY METASOMATIC MINERALIZATION. of the Sacramento Hill stock has produced a rock and mineralization as an ordinary case of contact depth at which large ore bodies are encountered As shown in those underground workings which which the closest examination does not always serve action about an intrusive stock is twofold., The in developments pushed toward the southeast. The are below the intermediate zone penetrated by oxi­ to distinguish with certainty from the altered por­ stock itself has been thoroughly altered and miner­ correspondence between the increasing depth of the dizing reagents, the sulphide minerals ascribable to phyry. Like the latter it is composed chiefly of alized and could not have originally supplied from larger ore bodies and the augmenting thickness, the early period of metasomatic alteration are com­ pyrite, quartz, and sericite. The schistose struc­ its own mass the large quantities of magnesia, from northwest to southeast, of the overlying mon pyrite and perhaps also a little chalcopyrite ture, however, is usually distinguishable and the sulphide of iron, and other constituents introduced wedge of relatively barren Naco limestone, while and sphalerite. The occurrence of some cerussite in rock does not exhibit the characteristic spotted into the adjacent limestones. The greater part at it can not be shown to be exact, is at least roughly the limestones suggests that galena may also occur, appearance which is often all that remains of the least of the mineralization must have taken place demonstrable and can scarcely be a chance coinci­ although this mineral has not been seen. Asso­ original porphyritic texture of the intrusive rock. after the porphyry had solidified. It is probable, dence. It contains a strong suggestion that the ciated with these sulphides are amphibole (trem- The alteration gradually fades out away from the although perhaps not in this case susceptible of maximum deposition of ore in the general zone olite), pyroxene (diopside), garnet (grossularite), porphyry, and at a distance of about a quarter of a definite proof, that the mineralization and meta­ thus far exploited was directly connected with the vesuvianite, quartz, and chlorite, in the limestones; mile the schists exhibit their normal character. morphism were effected by heated aqueous solutions. Escabrosa formation. quartz, sericite, chlorite, perhaps kaolin, and a How were the pyritic ores formed and whence The principal function of the porphyry, it is little epidote in the granite-porphyry; and quartz was their material derived? Not only are these believed, consisted in supplying heat to such RELATIONS TO GROUND WATER LEVEL. and sericite in the Final schist. questions of absorbing scientific interest, but in a solutions as rose from great depth and in thus The general ground-water level in the Bisbee dis­ The metamorphic minerals mentioned are not region where ore bodies lie deeply buried, and determining the locus of the chemical activity that trict is rather difficult of definition. As in other distributed uniformly through the limestone but where some knowledge of the relation of the ore to resulted in the deposition of the ore. arid regions it lies deep, and oxidation has been are arranged in zones about the porphyry mass geological structure may prevent the costly failures The source of the ore materials is not known. unable to convert all of the sulphides above it into of Sacramento Hill. Nearest the porphyry the of blind prospecting, they assume direct practical They may have risen through the Dividend fault what are commonly termed oxidized ores. As former limestone is now a fine-grained aggregate importance. Unfortunately they can not be fully from depths far below the bottom of the syncline country rock and ore do not constitute homogene­ consisting chiefly of quartz and calcite. Such is answered; but even partial answers may be of of Paleozoic rocks. They may have been collected ous material there is thus a very irregular down­ the rock of the Gardner shaft. The width of this service, if reasonable inductions from observed by solutions moving through one or more of the ward transition from the oxidized ores to the siliceous zone has not been accurately determined, facts be kept distinct from more or less speculative Paleozoic limestones on their way down to the sulphide masses involving a zone several hundred but may be roughly estimated at about 200 feet. hypotheses. locus of deposition. Lastly, they may have been feet in depth within which ores of both classes It is probably very irregular and is not sharply The spatial relation of the ores to the porphyry derived from both sources. The direct evidence occur. It may be pointed out in passing that these defined at its outer border. Although heavily mass of Sacramento Hill is such as to justify the on this question, however, is so meager and its conditions harmonize with other geological facts impregnated with pyrite it has not proved such conclusion that there is some genetic connection slight weight so easily shifted from one side to the that indicate a more humid climate during the favorable ground for the occurrence of ore bodies between them and the intrusive stock. The fact other by whatever bias may have been given to the Quaternary period and consequently a former as the zone next to be described. that the pyrite was formed at substantially the same observer's trend of thought by familiarity with higher ground-water level. Encircling the siliceous zone are pale-green time as amphibole, pyroxene, garnet, and vesuvian­ other fields of ore deposition, that an expression of Large masses of sulphide ore have been found altered limestones in which pyrite, tremolite, diop­ ite minerals characteristic of contact zones in lime­ choice between the principal hypotheses can have on the second level of the Copper Queen mine, less side, grossularite, and probably vesuvianite are the stones is not only additional evidence of such a little real value. Both are, in the nature of the than 200 feet below the surface, in the vicinity of characteristic minerals. In this zone quartz is general connection but indicates to some extent its case, speculative. the Dividend fault. In the Calumet and Arizona comparatively rare. Calcite, however, is abun­ specific character. mine, on the other hand, partial oxidation has dant, and may make up half or more of the altered Not all of the masses in the quadrangle resulting OXIDATION AND SECONDARY CONCENTRATION. extended to a depth of over 1050 feet, as is shown limestone. At its inner edge this zone grades from the intrusion and solidification of granitic Few if any of the ore bodies now known and by the abundance of cuprite and native copper, somewhat indefinitely into the siliceous zone. magma are associated with important mineraliza­ worked in the Bisbee quadrangle were formed with some limonite and malachite. In the Lowell About its circumference it passes by obscure gra­ tion. The granitic stock of Juniper Flat is con­ directly by the original mineralization discussed in mine oxidation has penetrated irregularly to a dations into the unmetamorphosed limestones of the nected with no conspicuous mineralization of the the preceding section. That process resulted, so depth of 1100 feet. At this depth the mine, region. The rock of this zone of metamorphic inclosing schists, and is not itself mineralized. It far as underground workings show, mainly in the formerly nearly dry, developed a flow of water silicates is softer than that of the inner siliceous is thus suggested that extensive mineralization may formation of bodies of cupriferous pyrite passing amounting to about 175,000 gallons a day. zone. It is frequently traversed by little irregular be dependent upon the juxtaposition of porphyry peripherally into metamorphosed and pyritized Within the transition zone between completely surfaces of shearing, so that it tends to break along and a particular rock limestone; but there are limestone. These bodies contained originally too oxidized and unaltered sulphide ores, which has a many curved surfaces into small fragments. The many porphyry dikes in the quadrangle that little copper to be classed as ore, as that term is maximum depth or thickness of about 900 feet, width of this zone can not be stated with precision cut limestones without producing mineralization. defined by present economic conditions of working. the oxidizing processes are controlled to a large on account of the indefinite character of its bound­ These, however, are relatively small masses, and Further concentration was necessary, and the profi­ extent by recent irregular fis curing and by the aries, but it may be very roughly estimated at this fact leads to the further tentative suggestion! table ores of to-day have been derived from these relative permeability of the various sulphide masses about 1000 feet. The zone is not, however, lim­ that extensive mineralization, competent for the! pyritic masses by secondary processes involving to generally descending solutions*. Fissures cutting ited in plan to a simple concentric band about the production of workable ore bodies, requires the? general oxidation with all its attendant chemical through masses of lean pyrite are almost invariably pdrphyry, but extends for a considerable distance fortunate conjunction of an intrusive mass of con­ phenomena, transfer of material, and the local accompanied by streaks of rich ore, often xcontain- to the northwest, toward the Czar shaft. siderable size with limestones. These conditions enrichment of certain portions of the sulphide ing chalcocite together with cuprite and native In general the zone in which the metamorphic are fulfilled in the vicinity of Sacramento Hill and masses. _, copper. Where there are several such fissures near silicates are developed is that in which most of the nowhere else in the quadrangle. Here, too, occur AGE OF THE COPPER ORES. one another, important ore bodies, occur. The ore bodies are found. In the western part of the the only important bodies of copper ore thus far general association of profitable ore with fissured, Copper Queen mine, however, extensive ore bodies discovered in the quadrangle. It might therefore All of the ore of the Bisbee quadrangle is post- broken, permeable ground is well recognized in occur in limestone that is perhaps outside of this possibly be concluded on this rather slender evi­ Pennsylvanian, since it is later than the granite- practical operations and turned to good account in zone. In other words, the deposition of metallic dence that the conditions named were all that were porphyry which cuts the Naco limestone. If, as underground exploration. sulphides appears to have had a wider range and necessary to produce the ores. But the case is not there is reason to suppose, the heat of the intruded Care has been taken to refer to the movement to have extended farther from the porphyry into quite so simple. mass of porphyry forming Sacramento Hill was a of the oxidizing solutions as generally downward. the fissured limestones than did the formation of Small bodies of copper ore occur at several factor in the original mineralization, then minerali­ There is abundant evidence, however, that for com­ the metamorphic silicates. points in the quadrangle in situations that show zation was probably initiated soon after the close of paratively short distances these solutions moved As metasomatic alteration has affected the entire no discoverable simple connection with granite- the Pennsylvanian epoch, perhaps in Permian or laterally and even upward. The occurrence of con­ Sacramento Hill stock, it is impossible to procure porphyry. Fissuring in the limestones is fre­ Triassic time. It may have continued with dimin­ siderable masses of lean pyrite completely enveloped any of the porphyry in its original condition for quently although not invariably accompanied ishing intensity into the Tertiary, That there has in rich ore consisting of chalcocite and the usual comparison with the altered rock. The intrusive by mineralization, even when no porphyry is also been some post-Comanche (i. e., late Creta­ minerals of the oxidized zone is fairly common. mass is impregnated with pyrite throughout. This near. At the Whitetail mine, for example, ore ceous or Tertiary) mineralization is shown by the Permeable or fissured masses of pyrite have been mineral is very abundant in the vicinity of the has been extracted from the vicinity of a bed­ occurrence of small mineralized veins in the Glance more or less thoroughly altered, while compact or contact with the limestone, but as the dump of the ding fault between the Abrigo and Martin lime­ conglomerate near Juniper Flat and south of Gold unfissured masses have retained to a large extent Copper King mine shows, may be nearly or quite stones. At the Wade Hampton claim, northwest Hill, by the introduction of chalcocite into the their original character and contain but little copper. as abundant in the areal center of the stock. In of Don Luis, near United States Land Monument same conglomerate in the vicinity of the Glance addition to the introduction of pyrite, the alter­ No. 3, ore has been taken from a hanging mine, and by the occurrence of a gold ore in the GENESIS OF THE COPPER DEPOSITS. ation involves a general recrystallization, which wall of Abrigo limestone faulted against Bolsa Morita formation at the JEaster, Sunday mine. GENERAL PROCESSES INVOLVED. in some places has ^obliterated the original por- quartzite. Hence it is concluded that fissures The secondary processes connected with oxida-, Two general processes have operated to form the phyritic texture, in others left it still faintly recog­ in the limestone are factors in the mineralization tion, which have transformed the low-grade pyritic ores as they are now exploited in the Bisbee quad­ nizable. The microscope shows that the quartz apart from any direct connection with intrusive masses near Bisbee into rich ore bodies, may have rangle. ' These are (1) metasomatic alteration, phenocrysts have recrystallized as quartz aggre­ masses. begun in Tertiary or even Cretaceous time, and including pyritic mineralization, and (2) oxidation gates, and that the feldspars and groundmass have The general relation of the great ore bodies of are still in progress. and its attendant phenomena of transportation and become areas of sericite, quartz, and pyrite, with the Copper Queen mine to the Dividend and Czar enrichment. Concerning the precise boundary occasionally a little epidote, chlorite, zircon, and faults has already been pointed out. The presence VALUE OF THE COPPER ORES. between these two general activities some difference rutile. Kaolin also occurs in microscopic aggre­ of these, and probably also of other less prominent The percentage of copper in the ore as mined is of opinion is possible, but as regards the essential gates with the sericite and may be in part a prod­ fissures, constituted an additional important factor to a very large extent subject to control by those share of each in the genesis of the ores there can be uct of the metasomatic alteration. Upon exposure in determining the initial mineralization from who direct mining operations. With ample facil­ no question. There are few known ore bodies in to the weather the pyrite in the metamorphosed which subsequent processes were to produce the ities for extensive and economical operation, the the Bisbee quadrangle which do not demonstrably porphyry oxidizes and the sericite, probably workable bodies of ore that now lie about the grade of ore that can be handled sinks lower and owe their value to the cooperation of both pro­ through the action of the sulphuric acid so formed, southwest side of Sacramento Hill. lower. Thus while a large mine may contain ore cesses. The existence of workable masses of ore becomes converted into kaolin. The porphyry as It is concluded that the original mineralization as rich as it did when first opened, the average 17 tenor of the ore now worked is usually very much would show if mined and treated directly as a gold 1 worked near Glance station. The mineralized por­ j water system. A portion of the water used for lower than formerly. ore, is unknown. tion of another constitutes the gold ore of the Eas­ domestic purposes is drawn from shallow wells in This almost self-evident fact is well illustrated Placer deposits. Small quantities of placer gold ter Sunday mine, which is utilized by the Copper the bottoms of the ravines within which the town by the Copper Queen mine. The ore first worked, have been obtained from the upper part of Gold Queen Company in its converters. For this pur­ is built. Such wells are obviously open to contami­ early in the eighties, averaged 23 per cent of copper. Gulch. This gold has been derived from the pose the amount of silica in the ore as delivered nation and their use is attended with grave danger. As the mine developed, as methods of treatment Glance conglomerate and concentrated in the sand at the smelter is, as has already been stated, not Another part of the supply comes from a spring in improved, and as transportation became less costly, and gravel of the present arroyo. It is not present allowed to fall below 84 per cent. Brewery Gulch, the water being brought into town the tenor of the ore was gradually reduced until in sufficient quantity to be of economic importance. Fluxes. The only flux used in the present in canvas bags on the backs of burros. The town the average at present is about 7 per cent, with a treatment of the Bisbee copper ores is a small has outgrown these primitive and unsanitary con­ range from 4 to 20 per cent. The minimum grade, LEAD. quantity of limestone, and of the purer varieties of ditions, and there is no good reason why the exam­ however, is mined only when it occurs with better Oerussite of Hendriclcs Gulch. This deposit, this rock suitable for smelting, the Bisbee quad­ ple of the Copper Queen Company should not be ore, or when it is particularly desirable for fluxing while not extensive, is of interest as being the first rangle affords an unlimited supply. The flux for followed and an abundant supply pumped from purposes. body of ore to be worked in the Warren mining the Copper Queen smelter in Bisbee is quarried one or more deep wells in the valley west of Naco. The average tenor of the ore from the Calumet district. The carbonate of lead occurs in impure, from the Naco limestone at a point about 200 yards While it is not probable that artesian water will be and Arizona mine in 1902 was about 10 per cent sandy form the so-called "sand carbonate" in from the furnaces. found in the Espinal Plain, such an occurrence is of copper, according to Mr. I. L. Merrill, but the Hendricks Gulch, about a quarter of a mile south Building stone. Rough blocks, used chiefly for not impossible, and it is reasonably certain that stopes were then recently opened and contained of Bisbee, and forms very irregular bunches in foundations and walls, have been quarried from wells put down to depths from 100 to 150 feet in some remarkably good oxidized ore. As develop­ the limestone in the vicinity of a fault fissure. It beds of Bolsa quartzite about half a mile west of the lower part of the plain lying between the San ment progresses it will probably be found econom­ is still worked on a small scale by lessees. None the business center of Bisbee, but the quarry is not Jose Mountains and the Naco Hills will reach ical to work ores of lower average grade. of this ore was observed in connection with the steadily worked. This stone is hard and durable abundant water which can be raised by pumping. MISCELLANEOUS METALLIFEROUS DEPOSITS. copper ores of the larger mines. but is not suitable for finished stone work. Good In the axial portion of the Sulphur Spring Val­ building stone might readily be quarried from ley wells encounter water in quantity at depths NON-METALLIFEROUS DEPOSITS. GOLD. the granite of Juniper Flat, but the lack of local varying from 100 to 200 feet. One well put down Easter Sunday mine. In this interesting deposit Clay and silica. These materials are chiefly demand for first-class stone and the cost of quarry­ by the Copper Queen Company near Douglas, the gold occurs free, rather irregularly distributed used in the form of an artificial plastic mixture ing and dressing it prevent any exploitation of this after passing through a layer of clay encountered a through some beds of light-colored quartzitic sand­ ganister employed for lining the Bessemer con­ resource. A fairly durable stone, easily worked, thin bed of water-bearing gravel at a depth of 355 stone belonging to the Morita formation. The verters. The clay used for this purpose in the could probably be obtained from some of the thick feet. The water from this stratum rose to within bulk of the ore occurs in a bed about 4 feet thick, Copper Queen smelter is stoped just above the sec­ beds of Escabrosa limestone. 3 feet of the surface, showing the existence of arte­ dipping about 55 degrees to the north-northeast, ond level in the southwestern part of the Copper sian conditions. As the bottom of the clays and WATER RESOURCES. but the mineralization is not entirely confined to Queen mine. It forms a considerable mass lying gravels has not yet been reached and as the width this bed. The sandstone has been irregularly just west of the Czar fault, and has resulted from In the early days of mining development much and slope of the valley are sufficient to give con­ fractured, probably during the post-Cretaceous the decomposition or alteration of some of the difficulty was experienced in obtaining sufficient siderable hydrostatic head, the prospects for finding folding, and the resulting small fissures have been sandy beds of the Abrigo limestone. The clay, water for the water-jackets of the furnaces, and at flowing wells are fairly good. In spite of the gen­ filled with veinlets of quartz and calcite. The which is somewhat arenaceous, passes, irregularly one time the project of pumping water from the erally arid climate large quantities of water gold is occasionally visible, usually in little calcite into loose, fine sand and into undecomposed sandy San Pedro River was seriously considered. Within annually pour from the mountains into this valley vugs stained with oxide of iron. It appears to limestone. Kaolin in various states of purity is the last few years, however, the Copper Queen and sink along its margins into the unconsolidated have been introduced into the beds subsequent to commonly associated with the oxidized copper ores Company, by sinking a well 118 feet deep, about a deposits with which it is partly filled. Whether fracturing. but is usually too much mixed with limonite or mile west of Naco, has succeeded in finding an ade­ any part of this water will rise to the surface by The gold ore of the Easter Sunday mine is bog manganese to serve as converter lining. quate flow of good water, which is pumped up to artesian flow in the middle of the valley depends reported to run about $30 per ton when sorted; Silica suitable for ganister occurs abundantly in Bisbee. The capacity of this well is 200 gallons upon the extent of the impervious clay strata but as the small quantity of ore thus far produced the quadrangle, the quartzitic sandstones of the a minute, which is suffiicient to meet the needs of shown by wells to exist in the axial portion of the has been accepted by the Copper Queen smelter Morita and Cintura formations affording an inex­ the company and to supply the Copper Queen valley. upon the condition that the silica shall not fall haustible supply in convenient proximity to the Hotel and the ice factory. The town of Bisbee, below 84 per cent, the actual tenor that the ore railroad. One of these beds is at present being however, is as yet unprovided with any general June, 1903. Bisbee.